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- Front Matter: Volume 6984
- Physics of Thin Films
- Thin Film Materials
- Technology of Thin Films
- Applications of Thin Films
Front Matter: Volume 6984
Front Matter: Volume 6984
Show abstract
This PDF file contains the front matter associated with SPIE
Proceedings Volume 6984, including the Title Page, Copyright
information, Table of Contents, Introduction (if any), and the
Conference Committee listing.
Physics of Thin Films
The structure and dielectrics of epitaxially strained BaRO3(R=Ti, Zr) thin films
Jinlong Tang,
Jun Zhu,
Jie Xiong,
et al.
Show abstract
The structure and static dielectric permittivity of BaRO3(R=Ti, Zr) thin films as a function of epitaxial strain are
determined by using first-principle density functional theory calculation based on pseudopotentials and a plane-wave
basis. It is found that BaTiO3 thin films under compressive misfit strain can be grown more easily than those under
tensile misfit strain, while thin films of BaZrO3 can be grown more easily under tensile strain. The static dielectric
permittivity of BaTiO3 thin films under different misfit strain is obtained by calculating optical phonon frequencies and
Born effective charges using density functional perturbation theory. The zero-temperature dielectric permittivity of ε33
increases to the maximal value under compressive misfit strain, while the ε11/22 reaches to its maximal value under tensile
misfit strain. For BaZrO3 thin films, the dielectric permittivity εr changes little. However, εr exhibits non-linear
characteristics under tensile strain, which reaches to the maximal value under misfit strain of ~1%. This unsymmetrical
dielectric behavior caused by strain is attributed to soften phonons in BaTiO3 or BaZrO3 thin films.
Stress effect on electronic characteristics in heterojunction of (n+)nanocrystalline/(p+)crystalline Si
Wensheng Wei
Show abstract
A heterojunction of heavy phosphorus doped hydrogenated nanocrystalline Si (nc-Si:H) film with p+-type crystalline Si
wafer was prepared and measured to investigate stress effect on electronic characteristics. According to electrical
experiments, the yielded structure was demonstrated as a semiconductor backward diode. Energy band gap of nc-Si:H
was inferred to equal that of amorphous Si:H because nanocrystals imbedded in amorphous Si:H matrices. Mechanical
stress effect on electronic characteristics for the operated unit was interpreted by stress-induced defect states since a mass
of defects distributed in inhomogenous material. Reverse current showing good linearly dependent on applied stress with
a effectual method of conversing mechanical signal to electronic one before breakdown was indicated.
Evaluation of carrier density distribution and population inversion caused by T-X scattering in GaAs/AlAs multi-quantum wells
Show abstract
We investigated the electric field dependence of photoluminescence (PL) spectra in four kinds of GaAs/AlAs multi-quantum
well (MQW) structures. Only one of them exhibited various PL spectra in spite of having a similar sample
structure in the MQW. The PL spectra reveal several signals in the shorter wavelength region due to the combination
effect of interface roughness and Γ-Χ scattering. We also estimated the carrier densities of excited states by observed PL
intensities and calculation of overlap integrals of wavefunctions between electron and heavy hole states. The observation
of PL signals from excited states in the MQW provides fruitful information on carrier densities and structural
imperfection of MQWs.
Phase diagrams and in-plane anisotropic misfit strains of (110) Ba0.6Sr0.4TiO3 thin films grown on (001) orthorhombic NdGaO3 substrate
Show abstract
Using Landau-Devonshire(LD)-type phenomenological model, we investigate the phase diagrams and in-plane
anisotropic misfit strains of single-domain single-crystal (110) Ba0.6Sr0.4TiO3 film epitaxially deposited on (001)
NdGaO3 substrate. Investigation indicates that film thickness plays a crucial role on formation of in-plane anisotropic
misfit strains and stable phases. As is consistent with results of experiment that anisotropic strains have greatly changes
with increase of film thickness. The anisotropic strains induce tetragonal phases which only contain in-plane spontaneous
polarization component. These phases do not exist in BST films of the same composition under isotropic strains.
Moreover, calculation manifests that anisotropic in-plane misfit strains are almost completely relaxed when film
thickness is larger than 600nm, which has been reported in experiment.
The first-principles study of Al adsorption on Si(001)2x1
C. B. Feng,
Z. Q. Ma,
F. Hong,
et al.
Show abstract
First-principles calculations have been performed to study the adsorption of Aluminium(Al) on the Si(001)2×1 surface.
The optimized geometries and electronic structures of the adsorption system were investigated. The adsorption energy at
various adsorption coverages(Θ) from half a monolayer(ML) to one monolayer has been calculated. The most stable
adsorption sites were consequently determined to be HH site and T3-T4 site, respectively. There is obvious evidence that
the asymmetric aspect of the Si-Si dimer becomes the symmetric one which has been observed at the coverage of 0.5ML
or 1ML. In addition, the bond length of Si-Si was found to be considerably elonged upon the Al adsorption. The work
function calculations have shown that the aspect of work-function change for the Si(001) surface due to the adsorption of
Al is different from that of the alkali metals adsorption reported in some previous works. The surface formation energy
was also calculated. The absolute value of the surface formation energy was found to decrease with increasing coverage
indicating that 1ML is not a saturation coverage. In order to shed light on the nature of the Al-Si bond and the character
of silicon surface, the density of states and band structure of the system were calculated.
Pulsed-laser deposition of thin Fe film on Cu(100): a kinetic Monte Carlo simulation
Juanmei Hu,
Fengmin Wu,
Yuzhang Fang
Show abstract
The initial stages of multilayer Fe thin film on Cu(100) surface prepared by pulsed-laser deposition(PLD) were simulated
by means of kinetic Monte Carlo(kMC) method. We focus on examining the effect of high instantaneous deposition rate
and energetic adatoms on nucleation and the surface roughness of Fe film on Cu(100) surface. The simulation results
show that high instantaneous deposition rate alone is insufficient to explain the layer-by-layer growth in PLD, and it is
the combination of the kinetic energy and high instantaneous deposition rate that leads to improved quality of the film
surface.
Evaluation of subband energy in TPD/DCM organic multiple quantum wells
Takayuki Takayuki,
Masaya Murata,
Motoki Haishi,
et al.
Show abstract
In this paper, we report fabrication and evaluation of an organic light emitting diode (OLED) with organic multiple
quantum wells (OMQWs). We fabricated the OMQWs using organic molecular beam deposition, consisting of TPD
(N,N'-bis(3-methilphenyl)-N.N-diphenyl benzidine) and DCM (4-(Dicyanomethilane)-2-methil-6-(p-dimethilamino-styryl)-
4H-pyran). We measured photoluminescence (PL) and electroluminescence (EL) properties to characterize the
OMQWs. In both measurements the peaking wavelengths clearly become shorter as the thickness of the QWs becomes
narrower. This result obviously indicates that subband states are achieved in the quantum wells. In addition, we did
numerical analysis to assign the effective mass of electrons in the OMQWs. Consequently, the effective mass of
electrons can be estimated as 0.05 m0.
Synthesis and characterization of SiO2 capped ZnCdS nanocrystals
GuoWei Yang,
DongMei Li,
XueFeng Zhu,
et al.
Show abstract
ZnCdS/SiO2 nanocrystals with core-shell structure were fabricated by Micro-emulsions method via the hydrolysis of tetraethyl
orthosilicate (TEOS). Using XRD and TEM, the size of capped nanocrystals was around 22nm with the uncaped
round 12nm. Emitting peaks in PL spectra of ZnCdS shifted from 390nm to 540nm by adjusting the proportion of Zn/Cd.
The water solubility and optical property are both obviously enhanced after the capsulation of SiO2.
Luminescence of rhodamine B doped in silica films by evaporation-induced self-assembly
Lanfang Yao,
Fengqin Lu,
Chunxiao Yue,
et al.
Show abstract
Rhodamine B was embedded in a matrix of mesoporous silica films by the sol-gel method. A precursor sol containing
tetraethoxysilane, ethanol, surfactant cetyltrimethylammonium bromide (CTAB), water, rhodamine B and acid catalyst
was prepared by sol-gel. Depositing the precursor sol on a substrate wherein evaporation of solvent and water causes the
formation of mesostructured films on the substrate surface by evaporation-induced self- assembly process. The
nanocomposites films were obtained by embedded rhodamine B in the pores of mesoporous silica films. The mesoporous
film was characterized by XRD and TEM, UV-VIS-NIR. The luminescence was measured and a red shift in the peak of
the luminescence spectra compared with rhodamine B in the film and rhodamine B in water was observed, which may be
interpreted as reflecting a decrease in the dipole moment of the exited molecule. The results show the luminescence
action of rhodamine B in nanopores approach to single molecule's. This relates to the restriction of nanopores to organic
molecules. The degree of aggregation decreases for the mesoporous silica films may be regarded as a hydroxylic,
relatively polar environment, less polar than water although controversy still exists on the role of water in causing
aggregation.
Determining band offset and interface charge density of hydrogenated nanocrystalline silicon/crystalline silicon heterojunction diode by C-V matching method
J. J. Lu,
Z. Z. Jiang,
J. Chen,
et al.
Show abstract
In this paper, we report the band offset and interface charge density properties of the nc-Si:H(n)/c-Si(p) heterojunction
(HJ) diode by the capacitance-voltage (C-V) measurement and theoretical modeling. By employing the ideal anisotype
HJ capacitance model and numerical C-V matching method, the band offset and heterostructure interface charge density
of the nc-Si:H/c-Si HJ have been obtained and analyzed. An interface charge density on the order of 1011 cm-2 is
estimated via the numerical C-V matching technique, and the low interface defect density has also been confirmed by the
frequency insensitive C-f results.
Temperature dependence of optical properties in AlInN thin films
Show abstract
X-ray absorption near-edge fine structure, optical transmission, and photoluminescence spectra have been measured on
an Al0.25In0.75N thin film. With the aid of a novel procedure developed for analyzing the transmission spectra, together
with a bandtail theory based on the calculation of density of occupied states and the carrier-phonon interaction, we have
obtained the temperature-dependent optical properties of the thin film, such as band gap and Urbach bandtail parameter.
Weak localization in indium nitride films
Show abstract
We have studied the weak localization (WL) effects in the electron accumulation layer on InN surface. Both the
spin-orbit relaxation time τso and the electron-phonon scattering time τe-ph have been extracted from the WL analysis.
We have observed that 1/τso increase with disorder and τe-ph exhibits a tendency to change gradually from the
characteristic dependence 1/τe-ph ∝ T3 in the pure case to the form of T2l-1 with increasing disorder.
Thin Film Materials
High density Si nanodots: fabrication and properties
J. Xu,
J. Zhou,
X. Li,
et al.
Show abstract
We propose an approach to achieve single layer of Si nanodots arrays on insulating layer by using KrF pulsed excimer
laser irradiation on ultra-thin hydrogenated amorphous silicon films followed by thermal annealing. Under the suitable
fabrication conditions, the area density of formed Si nanostructures can be higher than 1011cm-2 as revealed by AFM
images. The size of formed Si nanodots is 3-4 nm for sample with initial a-Si:H film thickness of 4 nm. Room
temperature visible light emission can be observed from laser irradiated a-Si:H film after thermal annealing. The results
on electron field emission properties were also presented in this paper.
Structural, electronic, and optical properties of Mn4Si7
Y. Gao,
R. S. Chen,
M. Y. Zhou,
et al.
Show abstract
Semiconducting high manganese silicides (HMS) have attracted great research interest in the past decades for potential
applications as novel optoelectronic and photovoltaic devices integrated on Si chips. The fundamental electronic
properties in HMS are still unclear, and the band-gap energy was reported to scatter from 0.42 eV to 0.98 eV in the past
decades. In this work, single phase semiconducting Mn4Si7 precipitates and thin films have been synthesized by ion
implantation. Optical absorption spectra obtained by transmission measurements demonstrated the existence of a direct
band gap in all samples. The band gap values varied in the range of 0.77 eV to 0.93 eV, corresponding to varied strain
states due to different microstructures. The electronic band structures of Mn4Si7 under different strain states have been
theoretically investigated by means of a full-potential linear augmented plane wave method and compared with the
experimental results. From ab initio calculations, the Mn4Si7 compound is found to be a pseudo-direct band-gap
semiconductor with a fundamental gap increasing linearly with the compression along c- or a-axis. This trend is in good
agreement with the experimental results.
The blue-shift effect of the ion-milling-formed HgCdTe photodiodes
F. X. Zha,
J. Shao
Show abstract
Ion milling-formed n-on-p diodes of HgCdTe were studied by photoluminescence spectroscopy. A sequence of spectra
measured across a square junction show that the luminescence peaks of the ion-eroded region shifted strongly to shorter
wavelength than those defined by monolithic material. This shift may be well interpreted in terms of Burstein-Moss
(BM) effect and is important to device fabrication.
Simultaneous double-sided deposition of long-length epitaxial CeO2 buffer layers for YBCO coated conductors
Jie Xiong,
Wenfeng Qin,
Jinlong Tang,
et al.
Show abstract
A reel-to-reel system which allows simultaneous deposition of both sided long length epitaxial CeO2 buffer layers on
biaxially textured Ni-5at.%W tape with direct-current (d.c.) reactive magnetron sputtering method is described.
Deposition is accomplished through two opposite holes in the cavity by inverted cylindrical magnetron (ICM) sputtering
guns. The films were characterized by means of x-ray diffraction (XRD), and atomic force microscope (AFM). The
samples exhibited good epitaixal growth with c-axis perpendicular to the substrate surface for both sides. FWHM values
of out-of-plane and in-plane for both sides were 3.2° and 3.1°, 5.3° and 5.1°, respectively. AFM observations revealed a
smooth, dense and crack-free surface morphology. Biaxially textured CeO2 buffer layers up to 100-m length could be
fabricated with production speed of about 1.2m/h. A 1-m CeO2 film was obtained with uniform thickness of 50nm, and
Δω of 3-3.5° and ΔΦ of 5-6°. Subsequently YSZ barrier and CeO2 cap layers were deposited to complete the buffer layer
structure via the same process. Epitaxial YBa2Cu3O7-δ (YBCO) films grown by d.c. sputtering technique on the short
prototype CeO2/YSZ/CeO2/NiW conductors yielded self-field critical current densities (Jc) as high as 1.3MA/cm2 at
77K. An Ic values of 103A/cm2 was obtained for double-sided YBCO coated conductors.
Epitaxial growth and electrical properties of Ba0.6Sr0.4TiO3 thin films with conductive La0.5Sr0.5CoO3 bottom electrodes
W. F. Qin,
J. Xiong,
J. Zhu,
et al.
Show abstract
Epitaxial Ba0.6Sr0.4TiO3 (BST) thin films were deposited on LaAlO3 (LAO) substrates with the conductive metallic oxide
La0.5Sr0.5CoO3 (LSCO) film as a bottom electrode by pulsed laser deposition (PLD). X-ray diffraction θ~2θ and Φ scan
showed that the epitaxial relationship of BST /LSCO /LAO was [001] BST//[001] LSCO//[001] LAO. The atomic force
microscope (AFM) revealed a smooth and crack-free surface of BST films on LSCO-coated LAO substrate with the
average grain size of 120 nm and the RMS of 1.564nm for BST films. Pt/BST/LSCO capacitor was fabricated to perform
Capacitance-Voltage measurement indicating good insulating characteristics. For epitaxial BST film, the dielectric
constant and dielectric loss were determined as 471 and 0.03, respectively. The tunabilty was 79.59% and the leakage
current was 2.63×10-7 A/cm2 under an applied filed of 200 kV/cm.
Synthesis, structure, and properties of Cu doped Bi4V2O11 via EDTA-citrate gel process
Ming Guo,
Hongmei Deng,
Pingxiong Yang
Show abstract
The oxide ion conductor material, Cu doped Bi4V2O11 (BICUVOX.10) powders were prepared by the combined EDTA
(ethylene diamine tetra acetic acid)-citrate synthesis technology. The dried gel was annealed at various temperatures
(400-600°C). Powders derived from dried precursor resulted in the mixed phases to BiVO4 and high temperature γ-phase
of Bi4V2O11 by heat-treating below 400°C, and furthermore, yielded only pure γ-phase above 500°C. A simple
surfactant-stabilized method was investigated for the preparation of well-dispersed nanoparticles. It was found that the
deagglomeration treatment to the precursor by surfactant polyethylene glycol (PEG) 4000 was effective in improving the
size distribution and annealing conditions of the BICUVOX.10 material.
Epitaxial growth and thermal dynamics of CeO2 buffer layer on textured Ni-W substrates for YBCO coated conductors
C. Y. Pan,
C. B. Cai,
L. L. Ying,
et al.
Show abstract
In present study, the biaxially textured CeO2 buffer layers on Ni-W substrates have been prepared by chemical solution
deposition (CSD) with cerium acetate as the starting precursor, mixed with solvents of Propionic acid, Isopropanol and
Acetylacetone. Typical XRD θ-2θ scans and the pole figure display well out-of-plane and in-plane textures of CeO2
films. SEM and AFM results suggest that the buffer layer have uniform and smooth surface. Meanwhile, the effects of
heating rate on CeO2 formation starting from the precursor solution have been studied using differential thermal analysis
(DTA). And the further analysis is given by XRD results for precursor xrogel at the corresponding temperature. Detailed
high temperature optical microscope (HTOM) photographs investigate the surface characteristics evolved with
temperature.
Electric field assisted low-temperature growth of SiGe on insulating films for future TFT
Masanobu Miyao,
Hiroshi Kanno,
Taizoh Sadoh
Show abstract
Development of new semiconductors with high mobility is strongly needed to realize future system-in-displays. To
achieve this, we have been investigating electric field assisted metal-induced lateral crystallization (MILC) of a-Si1-XGeX
(0<X<1) on insulating substrates. This realizes uniform crystal growth of SiGe with all Ge fractions. In addition, thin-film
transistors (TFTs) with Schottky source and drain structures were fabricated, which showed good ambipolar
operation characteristics. Present paper reviews such our recent progress of electric field assisted low temperature SiGe
growth and discusses the possible application to TFTs with high speed operation.
Surface morphology of (100) ZnTe: P layer homoepitaxially grown by horizontal MOVPE technique
K. Yamaguchi,
Y. Kuramitsu,
K. Saito,
et al.
Show abstract
The surface morphology and roughness of (100) P-doped ZnTe homoepitaxial layers grown by horizontal MOVPE using
tris-dimethylaminophosphorus have been investigated as a function of substrate temperature under two different source
transport rate conditions together with the photoluminescence property. The surface is marked by a dense ridging when
the growth is limited by reaction-kinetics on the grown surface, whereas the surfaces of the layers grown in the mass-transport limited regime show morphology consisted of a series of hillocks, independent of the transport rate. The growth
condition close to the transition part between the mass-transport and the surface-kinetics regimes provide an optimum
growth not only for achieving a minimum surface roughness, but also for a better photoluminescence property of the as-grown
P-doped ZnTe layer.
Synthesis of functionalized ZnS:Mn/ZnS nanocrystals
Dongmei Li,
Yiqiang Wang,
Guowei Yang,
et al.
Show abstract
ZnS:Mn/ZnS core/shell nanoparticles were pre-synthesized by microemulsions technique. To prepare water-soluble and
biocompatible nanoparticles, thioglycolic acid was directly added into the same reverse microemulsion system to modify
the surface of ZnS:Mn/ZnS nanoparticles. The functionalized ZnS:Mn/ZnS nanoparticles were coupled with carboxyl
and revealed farther luminescence enhancement at 600nm. The experiment results indicated that passivating of the
organic molecules and the polynuclear complex of Zinc may be the possible mechanism leading to enhancement of
luminescence.
A study on the properties of ramie fabrics modified by plasma
Zhiwen Wang,
Yanhe He,
Yihua Ma,
et al.
Show abstract
The experiment about ramie fabrics processed by oxygen plasma was introduced. The mass spectrum of residual gas was
measured by QMS, and quantities of hydrogen, carbon, oxygen and its compounds was observed from vacuum residual
gas. The microcosmic characteristic of ramie treated by oxygen plasma show that the surface of the ramie fibre was
effectively eroded by energetic particle and active molecules. It can be obviously seen from X-Ray diffraction analysis
that the crystalline-indices of ramie fibre were slightly reduced after processing in oxygen plasma. Experiment results
reveal that, with the increase of the processing time and power, the physical chemical properties such as wettability and
dyeability were obviously improved.
Structural investigation and barrier properties of a-C:H thin films on polymer by PECVD
Yuefei Zhang,
Xinchao Bian,
Qiang Chen,
et al.
Show abstract
In this paper, a thin amorphous hydrogenated carbon films were deposited on polyethylene terephthalate (PET) by means
of capacitive coupled RF plasma-enhanced chemical vapor deposition (PECVD) using a mixture of CH4 with Ar gas as a
source. The chemical composition of the deposited films were analyzed by fourier transform infrared (FTIR)
spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), laser Roman spectroscopy(LRS). And
the microgram of the film was detected atomic force microscopy (AFM). The barrier properties were examined by water
vapour permeation. The results show that the barrier performance of water vapor permeation in PET coated by
hydrogenated carbon film was decreased from 86.16 (g/m2d) to 10.68 (g/m2d) in experiments.
The structural properties of O and B-O ion implanted diamond films
X. J. Hu,
J. S. Ye,
Q. S. Lu,
et al.
Show abstract
The structural properties of B-O and O-implanted diamond films are investigated by using X-ray diffraction (XRD) and
Raman spectrum. The results show that a sharp (111) peak of diamond can be found in XRD pattern after annealing
under higher temperature, indicating the damaged diamond lattice produced by ion implantation has been restored. The
calculated grain size of B-O co-implanted diamond films is smaller than that of O-implanted diamond under 1000 °C
annealing, implying the introduction of boron into O-implanted diamond can hinder the grain growth under high
temperature annealing. Raman measurements show that higher temperature annealing can recover the damaged lattice.
Preparation and characterization of multiferroic CoFe2O4-Pb(Zr0.53Ti0.47)O3 composite films
Yanyan Zhu,
Xiaoyan Yang,
Jinrong Cheng,
et al.
Show abstract
Multiferroic double-layer CoFe2O4-Pb(Zr0.53Ti0.47)O3 (PZT) composite films have been fabricated by the hybrid process:
pulsed-laser deposition (PLD) and sol-gel method. The CoFe2O4 (CFO) layer with different thicknesses was deposited on
the substrates by PLD, and then the PZT layer was prepared on the top of the CFO layer by the sol-gel process. X-ray
diffraction shows that there are no other phases but spinel CFO and perovskite PZT phases in the films. It is observed
that the composite films demonstrate good ferroelectric and magnetic properties simultaneously. The composite films for
the CFO layer of 120 nm are found to have the best ferroelectric property with the enhanced ferromagnetization.
Fabrication and physical properties of high-quality zinc oxide thin films
Show abstract
In this paper, ZnO thin films with a polycrystalline preferential orientation and low surface roughness were successively
achieved on Si (100) substrate by RF magnetron sputtering techniques under optimized experimental parameters. In our
sputtered samples, the average grain size is around 15~23 nm calculated from Scherrer Formula, and transmittance in
visible range was over 80% measured by spectrophotometer, d33 equal to 27.5 pV/m measured by Piezoelectric Force
Microscopy (PFM), surface roughness is below 3.00 nm and a good (002) plane orientation growth observed from XRD
patterns. All the excellence properties of the ZnO thin films we acquired signal them are promising materials to be
applied in electronic devices.
The effect of sol concentration on 0.6BiFeO3-0.4PbTiO3 thin films prepared by sol-gel method
Jinyu Cai,
Shengwen Yu,
Jinrong Cheng,
et al.
Show abstract
A series of 0.6BiFeO3-0.4PbTiO3 (BFO-PT) thin films were fabricated by sol-gel technique with sol concentrations
varying from 0.2M to 0.4M. X-ray diffraction (XRD) and scanning electron microscope (SEM) were utilized to
characterize the structure and morphology of the BFO-PT films. The crystallinity of the films is improved with
increasing the BFO-PT sol concentration. The dielectric properties and leakage current density of BFO-PT films were
measured. The dielectric constants of all films are reasonably stable and the dielectric losses are below 5%. Considerably
lower leakage current density is obtained in our sol-gel films.
Electrical and optical properties of Na+-doped ZnO thin films prepared by sol-gel method
Ying-wei Li,
Chun-fang Lin,
Xiao Zhou,
et al.
Show abstract
Na+-doped ZnO thin films (Zn1-xNaxO, x=0-0.20) were prepared on Si<100> substrate by sol-gel method using zinc
acetate and sodium carbonate as starting materials. The electrical properties, including the conducting type and the
carrier concentration, as well as the optical properties of the so-obtained films were investigated by four-point probe van
der Pauw method and photoluminescence (PL) spectroscopy. After doping Na+, the conductive type of ZnO films
changed to p from n-type, indicating that Na+ can act as an acceptor to occupy the Zn2+ sites in ZnO lattice. The
resistivity, Hall mobility, and the hole concentration of the film with x=0.10 were 75.7 Ω•cm, 2.1 cm2/V s and
2.955×1016/cm3, respectively. The PL results showed that there were a narrow near-band-edge (NBE) emission line and a
broad deep-level (DL) emission for all the films with and without Na+ dopants. A slight blue-shift from about 383nm to
380nm of NBE line was observed for the films after doping Na+.
Nitrogen incorporation characteristics of 4H-SiC epitaxial layer
Renxu Jia,
Yimen Zhang,
Yuming Zhang,
et al.
Show abstract
Homoepitaxial growth of 4H-SiC on off-oriented Si-face (0001) 4H-SiC substrates is performed at 1580°C, 100 mbar
with rotation based on horizontal low-pressure hot-wall CVD (LP-HW-CVD) system to get high quality 4H-SiC
epilayers. The surface morphologies and structural and optical properties of 4H-SiC epilayers are characterized with
SEM, AFM, XRD and C-V measurement. By testing, the 4H-SiC epitaxial layer has a good crystalline structure and
mirror-like surface with few surface defects. N type 4H-SiC epilayers are obtained by in-situ doping of N2. The
Uniformity of doping concentration have been tested below 5%.
Thickness impact of aluminum and silicon on bow of silicon solar cells
L. Zhang,
W. Wu,
M. Li,
et al.
Show abstract
As the thickness of silicon solar cells becomes thinner, the cells are susceptible to bow because of the metallization of
metal and semiconductor on the front and rear contact. In this work, the thickness impacts of aluminum and silicon on
bow of the solar cell have been investigated with the perspective of deformation and strain.
Parameter optimization of silicon solar cell back surface field (BSF) formation
M. Li,
W. Wu,
Z. X. Zhao,
et al.
Show abstract
The BSF of mono-crystal silicon cell is studied in this paper. It simply states the principle and formation process of BSF,
and studies the evenness of BSF. In the experiment, we analyze BSF formed by taking different sintering temperature,
heating rate and setting different time, develop by chemical reagent and observe at high magnification scope, analyze
and get the optimal parameters of forming even BSF and further improve conversion efficiency of silicon chips.
Investigation of copper phthalocyanine based Schottky solar cells
Yu Zhang,
Weimin Shi,
Yuying Guo,
et al.
Show abstract
Copper phthalocyanine (CuPc) is an important versatile organic material. It has attracted more and more attention
because of its unusual stability and photoelectric properties. Copper phthalocyanine (CuPc) films, grown by vacuum
sublimation, were characterized with X ray diffraction (XRD), Raman and UV-VIS spectrometry. CuPc/Aluminum (Al)
Schottky solar cells were studied by varying the thickness of the CuPc layer from 30 nm to 130 nm. Optimum current
density-voltage characteristics of ITO/CuPc/Al was obtained for 110 nm thick CuPc layer, which revealed the Short
circuit current densities of 0.086 mA/cm2 and the Open circuit voltages of 300 mV. Bathocuproine (BCP), tris (8-hydroxyquinolato) aluminum and LiF were used respectively as buffer layer to discuss their influences on the electrical
characteristics of ITO/CuPc/Al Schottky solar cells. It was found that the insertion of a thin buffer layer would improve
the performance except LiF.
Annealing effects on exciton localization in GaNAs/GaAs epilayer
Z. L. Liu,
P. P. Chen,
L. L. Ma,
et al.
Show abstract
Rapid thermal annealing effects on GaNAs/GaAs epilayer with about 1.0% N are experimentally analyzed. Both the as-grown
and annealed samples are studied by photoluminescence at different temperature (11K~290K). Exciton
localization and delocalization are investigated in detail. It exhibits quite different optical properties for the localized and
delocalized excitons before and after annealing, this is attributed to the nitrogen reorganization inside the GaNAs layer,
which homogenizes initial nitrogen composition fluctuations present in the as-grown alloy.
Effect of annealing temperature on the structural and optical properties of Al-doped ZnO films by RF magnetron sputtering
Yuebo Wu,
Bo Huang,
Liangtang Zhang,
et al.
Show abstract
The Al-doped ZnO (AZO) films were deposited on the glass substrates by RF magnetron sputtering. After the deposition,
the films were annealed in N2 at several temperatures from 500°C to 800°C for 60 minutes respectively. The crystal
structures of the AZO films were characterized and analyzed by X-ray diffraction. The surface morphologies of the films
were observed by SEM. The transmission spectra of the films were measured using a spectrophotometer within the range
from 200 to 800 nm at room temperature. The results indicate each of the films has a preferential c-axis orientation and
the grain size increases with annealing temperature increasing. All the films exhibit a high transmittance in visible region
and have sharp ultraviolet absorption characteristics.
Investigation on the mechanical properties of P-doped nc-Si:H films
Li Wang,
Jinliang Wang,
Jinzhao Lin,
et al.
Show abstract
This paper reports mechanical properties of P-doped hydrogenated nanocrystalline silicon (nc-Si:H) films prepared by
PECVD in different conditions. The basic mechanical properties of nanocrystalline silicon thin films are evaluated from
load, hardness and modulus curves using a nanoindentation instrument. The effect of P-doping rate and types of
substrates on mechanical properties is discussed. It is indicated that proper phosphorus-doped nanocrystalline silicon
films have lower carrying capacity, but they hold ideal interface combination strength and lower surface roughness;
Nanocrystalline silicon thin films on glass substrates have better distortion coordination and film-substrate bonding
strength compared to films on silicon substrates. In addition, it is also expected that the thickness of thin films can be
roughly estimated by the first obvious step's position on the Load-depth curves.
Optical properties of Li2B4O7 polycrystalline films prepared by screen-painting method
LiJuan Jia,
Qian Wang,
Jikang Jian,
et al.
Show abstract
Li2B4O7 thin films were fabricated by screen-painting method on graphite substrates, and annealed at 300°C, 500°C,
600°C and 800°C for 3 hours, respectively. X-ray diffraction analyses show that the crystallinity of the films depends on
the annealing temperature. The X-ray diffraction reflections of films become stronger after annealed at 300°C while a
strong peak of graphite substrate appears. The XRD reflections of Li2B4O7 layers broaden and weaken when annealed at
500°C-600°C.When the sample was annealed at 800°C, the XRD peaks of films become sharper and stronger again.
These results indicate that the optimum annealing temperature for Li2B4O7 thin films is 300°C or above 600°C. The SEM
observations shows that the grain size is larger after annealed at 300°C. We also studied the optical absorption properties
of the Li2B4O7 films by the UV-VIS analysis.
Size dependence of tunneling magnetoresistance in self-assembled nanoparticle arrays
Yanmin Yang,
Yingbin Lin,
Caiqin Wu,
et al.
Show abstract
In this paper, size dependence of tunneling magneto resistance (TMR) in nano particle arrays was studied with Monte
Carlo simulation and resistor network model. When the electrode was applied along the X-axis, TMR increased as the
length LJ increasing and then decreased in particle arrays, while TMR decreased with increasing length LJ as the
electrode was along the Y-axis.
Growth of highly (h00) oriented barium strontium titanate films on silicon substrates using conducting LaNiO3 electrode
Show abstract
(Ba,Sr)TiO3 (BST) thin films were deposited on the conducting perovskite LaNiO3 electrode by radio-frequency (rf)
magnetron sputtering technique. To investigate the crystalline of BST films, the substrate temperatures (Td) in the range
of 100°C-700°C were applied. The transition from amorphous phase to polycrystalline phase for the films occurred at
low growth temperature 300°C. When the growth temperature approached 500°C, highly (h00)-oriented films were
obtained. The relative dielectric constant (εr) increased rapidly with enhancing growth temperature because of improved
crystallinity, and showed slowly increase above 500°C. In addition, the capacitance-voltage characteristics were studied
with various growth temperatures. The tunability increased largely with good crystallinity. This can be attributed to
increased dielectric constants.
Preparation and photoelectric properties of ZnPc-PPV/TAZnPc films
Junzhi Zhang,
Yue Shen,
Feng Gu,
et al.
Show abstract
A soluble partly linked PPV derivative of ZnPc (zinc phthalocyanine) and PPV (poly-phenylene vinylene) was
synthesized (ZnPc-PPV) and characterized by electronic absorption and fluorescence spectrum. ZnPc-PPV exhibits high
solubility and excellent film-forming property. The absorption spectra of ZnPc-PPV show intense absorption bands at
320 nm and 680 nm, which come from the characteristic absorption bands of Poly (α-hydroxyl-p-phenyl-acetyl) and
ZnPc, respectively. The current-voltage characteristics of ZnPc-PPV blended with TAZnPc (ZnPc-PPV/TAZnPc) films
under irradiation was 4.45 times higher than that in the dark.
Spectroscopic ellipsometry measurement and simulation of mesoporous TiO2 multilayer films
Lu Huang,
Yue Shen,
Feng Gu,
et al.
Show abstract
Ordered mesoporous titania thin films have been grown on Si and ITO substrates by evaporation-induced self-assembly
(EISA) progress. The films have well-organized honeycomb structures and consisted of anatase nanocrystallites
according to the results of HRTEM. Between the regions of wavelength from 400 nm to 1250 nm, the simulation data of
the refractive index coefficient (n) is decreased with the wavelength increasing. In contrast, the simulation of the
extinction coefficient (k) is decreased quickly before the wavelength of 700 nm, and it is enhanced gradually with the
wavelength increasing after the extreme value at about 700 nm. Simulation of n and k of mesoporous TiO2 multilayer
films from the data of transmission spectra are helpful to remedy the lack of spectroscopic ellipsometry measurement,
especially in the regions of weak absorbance.
Structural, electrical, and optical characterization of nanocrystalline diamond films deposited by HFCVD method
Show abstract
The structure, electrical and optical properties of nano-crystalline diamond (NCD) films deposited by hot-filament
chemical vapor deposition (HFCVD) method, are reported. The influence of the carbon concentration during the film
deposition on the Raman scattering, optical gap, optical constants (n and k) and dark-current is investigated. Under a
higher carbon concentration during deposition, the NCD film obtained with a smaller grain size, has a lower optical gap,
refractive index and electrical resistivity. These changes with the carbon concentration are attributed to the high amount
of sp2 bonded carbons and other non-diamond phase, which is confirmed by Raman scattering measurements.
Influence of substrates on the nucleation behaviour of nanocrystalline diamond films
Show abstract
Nanocrystalline diamond (NCD) films have been deposited by hot filament chemical vapour deposition (HFCVD) from
acetone/hydrogen gas mixtures on a variety of substrates such as silicon wafers and polycrystalline diamond. The
influence of the chemical nature of the substrate, the roughness, and the pretreatment of the substrates on the nucleation
and the bulk structure of the NCD films are investigated. By means of X-ray diffraction (XRD) and Raman spectroscopy
it is shown that the bulk properties of the films are not affected by the status of the substrate although these have a strong
influence on the nucleation behaviour.
Ellipsometric study of CVD diamond films prepared with various grain sizes
Show abstract
Diamond films with various grain sizes are grown on silicon substrates by hot-filament chemical vapor deposition
method. Scanning electron microscopy (SEM) measurement shows that the films consist of diamond grain with an
average crystallite size of 1.4-0.1μm. The optical and structural properties of diamond films are investigated by
spectroscopic phase modulated ellipsometer in the energy range of 0.8-1.5eV. A three-layer model, Si/diamond
film/diamond film + void/, is applied to diamond film based on Bruggeman effective-medium approximation and New
Amorphous dispersion formula which is a rewrite of Forouhi-Bloomer formulation. By fitting spectroscopic
characteristics (Ψ,Δ) with Levenberg-Marquardt regression algorithm, the energy band gap and refractive index are
obtained, along with the film thickness, bulk void fraction and roughness layer. The study indicates that both energy
band gap and refractive index decrease when grain size reduces due to the raise of disorder sp2 bonded carbon. The result
on the Raman scattering measurement is consistent with the fitting result of spectroscopic ellipsometer.
Effect of heat treatment on the property of CuInS2 thin film prepared by chemical bath deposition
Show abstract
Uncrystallized copper indium disulphide (CuInS2) thin films have been deposited on ITO glass by chemical bath
deposition (CBD) in acid conditions. Then polycrystalline CuInS2 films were obtained after sulfuration in sulfur
atmosphere at 300°C, 350°C, 400°C and 450°C for 1.5 hours respectively. The films have been characterized by X-Ray
diffraction (XRD), scanning electronic microscopy (SEM), precision surface profiler, energy dispersive X-ray analysis
(EDX) and Hall effect measurement system. The results show that with the raising of heat treatment temperature the
crystal degree and electrical property of the film are improved. Our work demonstrates the chemical bath deposition in
acid conditions is a promising method for deposition of CuInS2 thin films for solar cells.
Properties of compositionally graded (Pb,Sr)TiO3 thin films for tunable microwave device application
Dongyi Zhou,
Wenbiao Wu,
Dengren Jin,
et al.
Show abstract
Multilayered (Pb1-xSrx)TiO3 thin films consisted of uniform PST(x) and sandwich-like compositionally graded PST80-
60-80 were fabricated on Pt/Ti/SiO2/Si substrates by coating the solutions with different Sr contents(60≤Sr(mol%)≤80),
respectively. Their structural and dielectric properties were investigated. Both uniform and compositionally graded films
crystallized into a perovskite structure with no second phase found after post-deposition annealing. Among uniform
films, the PST60 films showed the highest dielectric constant and tunability, but low figure of merit(FOM) due to
relatively higher dielectric loss. For the sake of bringing down the dielectric loss, the PST60 thin films were sandwiched
by PST80 thin layer, resulting in a decrease in dielectric loss and slight decrease in tunability. Besides the improvement
of FOM, the temperature stability of graded PST80-60-80 thin films was also enhanced.
Fabrication and properties study of Cu(In1-xGax)Se2 films by vacuum evaporation
Ai-min Li,
Juan Qin,
Wei-min Shi,
et al.
Show abstract
The Cu(In1-xGax)Se2 (CIGS) thin films were prepared by stacked elemental layers (SEL) method via vacuum
evaporation. X-ray diffraction (XRD) analysis showed that the films were consisted of chalcopyrite CIGS phase.
Scanning electronic microscopy indicated that the film surface was compact and the grain size was about 1μm. It was
found that CIGS film with preparation sequence Ga/In/Cu/Se was of best crystalline quality. Besides, adding Ga greatly
improved the crystallinity for all sequences compared with CIS films at the same annealing temperature.
Influence of DC Joule heating treatment on the GMI effect in Fe-Co-Nb-Si-B ribbons
Qikui Man,
Yunzhang Fang,
Huaijun Sun,
et al.
Show abstract
The influence of DC Joule heating treatment on the longitudinally driven giant magneto-impedance (GMI)effect of
Fe36Co36Nb4Si4.8B19.2 ribbons was studied, and the GMI effect responded sensitively (the sensitivity was as high as
2440.2%/A•m-1) to weak magnetic field was detected after annealed at current density of 3.2×107A/m2 for 600-second.
The experimental results showed that the sensitivity is closely related to annealing current density, driven current
frequency and eroded thickness.
Sol-gel preparation and characterization of transparent GdTaO4: Eu3+ thick films
Show abstract
Transparent luminescent films have been believed to have the potential applications in high spatial resolution X-ray
imaging system. However, it is usually restricted by the thickness of the film. Instead of alkoxide, GdTaO4:Eu3+ film
with a thickness of about 0.8 μm was prepared from an inorganic salt-2-methoxyethanol solution containing
polyvinylpyrrolidone (PVP) as an additive via single-step spin coating. The whole process was carried out without inert
atmosphere which is necessary for alkoxides. The fired film is optically transparent and crack-free, and exhibits a strong
luminescence at 611 nm under X-ray excitation.
Fabrication and photoluminescence properties of ST-401 plastic scintillation films
Show abstract
ST-401 plastic scintillation films were prepared by spin coating. The self-supporting films were obtained and they
displayed a satisfactory appearance in terms of uniformity and transparence. The relationship between
photoluminescence (PL) property and film thickness was presented and the influence of preheat temperature of coating
solution on PL intensity of the film was discussed in detail. The results indicated that the PL intensity increased whereas
PL intensity ratio of PTP to POPOP decreases with the increase of the film thickness. PL intensity of the film at 423 nm
was improved remarkably by heating the coating solution, which makes ST-401 films have a promising application in
the detection of low-intensity pulsed fission neutron flux.
Pockels effect in GaN/AlxGa1-xN superlattice with different quantum structures
Show abstract
The linear electro-optic (Pockels) effect of wurtzite gallium nitride (GaN) films and six-period GaN/AlxGa1-xN
superlattices with different quantum structures were demonstrated by a polarization-maintaining fiber-optical Mach-Zehnder interferometer system with an incident light wavelength of 1.55μm. The samples were prepared on (0001)
sapphire substrate by low-temperature metalorganic chemical vapor deposition (MOCVD). The measured coefficients of
the GaN/AlxGa1-xN superlattices are much larger than those of bulk material. Taking advantage of the strong field
localization due to resonances, GaN/AlxGa1-xN SL can be proposed to engineer the nonlinear responses.
Structures and optical properties of indium doped SrTiO3 thin films by oxygen plasma-assisted pulsed laser deposition
Yiwen Zhang,
Xiaomin Li,
Weidong Yu,
et al.
Show abstract
Undoped and In-doped SrInxTi1-xO3(x=0, 0.1, 0.2) films have been deposited on Si(100) and quartz substrates by oxygen
plasma-assisted pulsed laser deposition (PLD). Effects of indium doping on the crystallinity and the optical energy band
gap of SrTiO3 (STO) films were investigated. Results indicate that undoped STO film is of rather good crystallinity and
low defects concentration. However indium doping deteriorates the crystallinity of the STO film, and results in the
roughening of the film surface. Moreover the a-axis length monotonically increases when increasing In content. For all
the films, the average transmission in the visible wavelength region (λ=400-800nm) is over 75%. The optical energy
band gap of STO thin films, measured from transmittance spectra, changes from 3.67eV to 3.93eV by indium doping.
Fluorescent polymeric nanoparticles fabricated by plasma polymerization under atmospheric pressure and room temperature
Show abstract
Fluorescent pyrrole nanoparticles were first synthesized through plasma polymerization under atmospheric pressure and
room temperature. The spherical polypyrrole nanoparticles with a diameter of 100-200 nm are uniformly distributed.
FTIR was used to investigate the structure of atmospheric pressure plasma polymerized polypyrrole nanoparticles
(AP-PPy nanoparticles). The result indicates that the nanoparticles keep a better reservation of the pyrrole structure. The
effect of power on the optical property of AP-PPy nanoparticles was analysised with UV-Visble absorption and PL
spectra. Polarization induced coplanarization of pyrrole and high level of chain stock during the nucleation and growth
of nanoparticles. These lead to a better conjugation of chains, and avoid the aggregation quench. Thus polypyrrole
nanoparticles exhibit a strong fluorescence emission at the range of 415nm to 450nm with different power. This
technology will help to the realization of practical optoelectronic nanodevice applications of fluorescent polymeric
nanoparticles.
Correlation between crystalline qualities and resistive switching effects of La0.7Sr0.3MnO3 films
Feng Wu,
Xiaomin Li,
Weidong Yu,
et al.
Show abstract
In this work, La0.7Sr0.3MnO3 (LSMO) thin films have been prepared on Pt/Ti/SiO2/Si substrates at different substrate
temperatures by pulsed laser deposition (PLD) method. Nonlinear current-voltage (I-V) behavior and the electric-pulse-induced
resistance change were observed in all Ag/LSMO/Pt heterostructures. Resistive switching properties exhibit
very strong dependences on the film crystalline qualities. Also, models for interpreting the results were also proposed.
Effects of TiO2 buffer layers on the dielectric and tunable properties of Ba0.6Sr0.4TiO3 thin films prepared by pulsed laser deposition
Jia Gong,
Jinrong Cheng,
Shengwen Yu,
et al.
Show abstract
The dielectric properties of Ba0.6Sr0.4TiO3 (BST) thin films were greatly affected by interfacial layers between the
electrodes and BST thin films. Our previous work shows that the dielectric loss of the BST system can be decreased by
an excess of Ti contents. In this paper, TiO2 buffer layers were grown between BST thin films and the Pt coated silicon
substrate, which are expected to improve the interfacial conditions by providing a certain amount of titanium. Both BST
and TiO2 films were prepared by pulsed laser deposition. Different substrate temperatures of 550°C, 600°C, 650°C,
700°C and different oxygen pressures of 1mTorr, 10mTorr, and 100mTorr were used for the deposition of TiO2 buffer
layers. XRD pattern shows that all the samples have crystallized into the perovskite structure and the (110) peaks
become sharper with increasing substrate temperature, indicating better crystallization along this direction. The increased
tunability and lower loss of BST thin films with TiO2 buffer layers prepared at the optimized temperature and oxygen
pressure achieve about 45.9% and 0.01 at the field of 200kV/cm and 1 MHz. The figure of merit of BST thin films is
significantly improved to 45.9 upon using TiO2 buffer layers, which is only about 18.2 for BST thin films prepared
directly on the substrates. Our results indicate that TiO2 buffered BST thin films are expected to have better dielectric
and tunable properties.
Study of lithium diffusion through vanadium pentoxide aerogel
Airong Wang,
Guangming Wu,
Hui-yu Yang,
et al.
Show abstract
Good electrode materials play an important part in rechargeable Li batteries. In this paper, safe and inexpensive
vanadium pentoxide (V2O5) aerogel materials were used as cathode materials. We discussed preparation of the films and
lithium ion diffusion at the interface between the cathode and electrolyte by potential-step current transient technique and
digital simulations. The results showed that diffusion coefficient (DLi) of the V2O5 aerogel film was 9.18×10-14cm2/s and
exchange current was 12.5×10-6A at potential step 3.6~3.5VLi/Li+.
The synthesis and properties of nano-SnO2 thin film by sol-gel
Sumei Qin,
Ziyang Tong,
Ming Guo,
et al.
Show abstract
Tin oxide nano-films with different grain-diameter have been synthesized by the modified sol-gel method, used tin
chloride dihydrate (SnCl2•2H2O) as main materials and ethanol as solvent. After magnetic agitation and ageing, tin oxide
(SnO2) thin films were prepared on silicon substrates by spin-coat process and then annealed at different temperature in
oxygen atmosphere. The obtained samples are polycrystalline films with rutile structure and have preferred orientation of
(110) direction. The crystal structure, the morphology, and the optical property of the thin films were characterized by X-ray
diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared Spectrometer (FT-IR).
Infrared dielectric properties of BaTiO3 ultrathin films
Show abstract
Using high accurate infrared spectroscopic ellipsometry, the infrared dielectric constants of BaTiO3 ultrathin films are
obtained in the temperature ranging from 20 to 150°C, which were deposited on Pt-Ti-SiO2-Si substrate by radio
frequency magnetron sputtering. The high frequency dielectric function of the BaTiO3 ultrathin films shows the
temperature dependence from the tetragonal to the cubic phase transition. The results suggest that the temperature
dependence of the BaTiO3 ultrathin films' infrared dielectric properties should be considered in the technological
applications and theoretical investigations.
MOS capacitance properties of silicon-based PZT thin films
Xiuhua Zhang,
Meirong Shi,
Sumei Qin,
et al.
Show abstract
Ferroelectric Pb(Zr0.53Ti0.47)O3 (PZT) thin films were grown on silicon substrates by modified So1-Gel method using
C4H6O4Pb•3H2O, ZrO(NO3)2•2H2O and Ti(OC4H9) as raw materials. PbTiO3 (PT) thin film was introduced as buffer
layer. The microstructures of PZT thin films were characterized by XRD and SEM. Electrical properties such as C-V and
leakage current characteristics of the films was investigated. The results show that PT buffer layer was helpful to
improve the dielectric and ferroelectric properties of PZT thin films. PT buffer layer prevented the interface reaction and
reduced the leakage current density of PZT/PT/Si structure about 10-2 compared with that of PZT/Si structure.
Influence of substrate temperature on properties of tin sulfide thin films
Yuying Guo,
Weimin Shi,
Yu Zhang,
et al.
Show abstract
Tin sulfide (SnS) thin films for solar cells were deposited by vacuum evaporation at different substrate temperatures in a
range of 20~200°C. The films were characterized with X-ray diffraction (XRD) and scanning electron microscopy
(SEM) for structural analysis. The electrical and optical properties were also investigated. Under the substrate
temperature of 150°C, the obtained SnS thin film was in orthorhombic structure with a grain size of 0.5 μm and
composition of Sn:S =1:1. The measurement results from hot probe method showed p-type nature for the deposited
films. Dark-conductivity and photo-conductivity were 0.01Ω-1•cm-1 and 0.08Ω-1•cm-1, respectively. The optical band-gap
energy of the films was estimated to be 1.402 eV.
Investigations on Sb2O3 doped-SnS thin films prepared by vacuum evaporation
Yuying Guo,
Weimin Shi,
Yu Zhang,
et al.
Show abstract
Tin sulfide (SnS) is one of promising candidate materials for low-cost thin film solar cells because of its high absorption
coefficient and suitable band-gap. The aim of this paper is to study the properties of doped-SnS thin films prepared by
vacuum evaporation. Sb2O3 was used as the doping source (the weight ratio of Sb2O3 to SnS in the range from 0.1% to
0.8%). And then the Sb2O3-doped SnS thin films were annealed in the hydrogen
atmosphere at different temperatures and
times. The structure of all the samples was characterized by X-ray diffraction (XRD). The electrical properties of SnS
thin films were investigated as well. From the results, the optimum doping content of Sb2O3
was 0.2% in weight, and the
resistivity of the doped-SnS film was 42Ω•cm while that of the pure-SnS film was 99Ω•cm. In addition, the film
resistivity of Sb2O3-doped SnS film decreased to 24Ω•cm with the best annealing conditions of 400°C and 3 hours.
Magnetic behavior of Fe-based nanostructures combined with the ordered porous Al2O3 film
Chenxia You,
Jiancheng Zhang,
Zhenwei Song,
et al.
Show abstract
Fe-based nanostructures have been synthesized by two different template-directed methods: electrochemical and
chemical deposition. The products exhibit unique magnetic properties. The two approaches are firstly compared with
each other through the characterization of the crystalline structure, morphology and magnetic properties of the as-prepared
products using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray
diffraction (XRD), selected area electron diffraction (SAED), energy dispersive analysis (EDS) and physics property
measurement system (PPMS). The results show that the nanowires can be obtained by electrochemical deposition while
the nanotubes obtained by chemical deposition. The growth mechanism is also briefly discussed.
Growth and characterization of AlN thin films on free-standing diamond substrates
Show abstract
The free-standing diamond films with a smooth and high quality nucleation side were prepared by hot filament chemical
vapor deposition (HFCVD) method. The nucleation side of the films had a mean surface roughness of 1.6nm.AlN films
were then deposited on the nucleation side of the above diamond films by radio-frequency (RF) reactive magnetron
sputtering method. The structure characteristics of AlN films deposited under different working pressure (p), sputtering
power (w) and sputtering plasma composition were studied. The optimized parameters for the growth of high c-axis
orientation AlN films were obtained: p=0.2Pa,w=600w and Ar/N2=3:1.Surface morphologies of AlN films deposited
under these parameter, tested by means of atomic force microscope (AFM), showed that the mean surface roughness was
about 4.1nm.It also had a strong c-axis orientation structure investigated by X-ray diffraction (XRD). All results above
suggested that the AlN/diamond structure prepared in this work was ideal for the application of high frequency surface
acoustic wave devices (SAW) device.
Growth and characterization of Li-doped ZnO thin films on nanocrystalline diamond substrates
Show abstract
Nanocrystalline diamond(NCD) films with a mean surface roughness of 23.8 nm were grown on silicon substrates in a
hot filament chemical vapor deposition(HFCVD) system. Then,
Zn1-xLixO (x=0, 0.05, 0.10, 0.15) films were deposited on
these NCD films by radio-frequency(RF) reactive magnetron sputtering method. When x was 0.1, the Li-doped ZnO film
had a larger resistivity more than 108Ω•cm obtained from Hall effect measurement. All the Zn1-xLixO films had a strong
c-axis orientation structure determined by X-ray diffraction (XRD). The above results suggested that the Li-doped ZnO
film/NCD structure prepared in this work was attractive for the application of high frequency surface acoustic wave
(SAW) devices.
Effects of high magnetic field on the properties of hot-filament CVD diamond films
Show abstract
A hot filament chemical vapor deposition (HFCVD) apparatus, combined with a cyro-cooled superconductor magnet,
were recently developed. Nanocrystalline diamond (NCD) films were prepared by above HFCVD apparatus either with
or without high magnetic field. Surface morphologies of these films were characterized by means of atomic force
microscope (AFM). The results indicated that the mean surface roughness and grain size of these films decreased when
the magnetic field varied from 0T to 4T. From Raman scattering measurement, all films prepared either with or without
high magnetic field exhibit NCD features. These NCD features of the sample prepared with 4T magnetic field was
obviously pronounced. The structure of these films was also investigated by X-ray diffraction (XRD).
Technology of Thin Films
New approach to formation of nanopore on SOI: SiC/Si heteroepitaxial growth by supersonic jet CVD
Yoshifumi Ikoma,
Kenta Ono,
Mutsunori Uenuma,
et al.
Show abstract
We report on a new nanopore formation technique by utilizing SiC/Si(100) heteroepitaxial growth. The SiC growth onto
Silicon-On-Insulator substrates was carried out by CH3SiH3 supersonic jet chemical vapor deposition. Inverse pyramidal
pits surrounded by {111} facets were created in the top Si layer during the SiC heteroepitaxial growth. Randomly
distributed nanopores with the diameter of ~10 nm were obtained in the top ~180 nm thick Si layer by removing the
buried oxide layer under the pits. It was found that the oxide patterns on the top Si layer were effective for the site-control
of the nanopore formation.
A methyl BN film by using tris-di-methyl-amino-boron (TMAB) for future low-K interlayer
H. Aoki,
S. Tokuyama,
M. K. Mazumder,
et al.
Show abstract
A silicon-oxide-based porous methyl material such as a porous SiOCH has been investigated as a Low-K film for post
45nm node generation. However, low young modulus of porous Low-K films is serious issues in Cu/Low-K
interconnection. We have investigated Low-K material of Boron Nitride containing methyl (Methyl Boron Nitride) by
using Tris-di-methyl-amino-boron (TMAB) gas. This paper reports on properties of a Methyl BN film by TMAB. We
have succeeded in Low-K material (K value:2.2) with Young modulus >26GPa.
Fabrication and optical properties of ferroelectric microcavities fabricated by chemical solution deposition
Show abstract
The quasi-periodical quaternary ferroelectric Bragg reflectors were fabricated by using precursor solution with PEG
additive. For PZT, both PEG and PVP are suitable polymers in fabrication of periodical structures based on one single
chemical solution, while for BST the optical performance of the BST multilayers derived from the solution containing
PVP is better than that of the BST multilayers prepared using the PEG-containing solution. One or two defect layers
were inserted into the multilayers. The single cavity BST multilayer shows well-defined resonant cavity mode occurring
in the reflection stop band while the BST multilayer with double cavities exhibit two coupled cavity modes on the high
reflection band.
The effects of buffer layers on the growth of smooth relaxed SiGe thin films
Shuqi Zheng
Show abstract
The smooth relaxed SiGe films were fabricated on Si(001) substrate using 30nm thick buffer layers by molecular beam
epitaxial (MBE). The buffer layers were fabricated as followings: first deposited 20nm thick SiGe alloy layer at 550°C,
then 10nm Si buffer was deposited at 400°C. After the buffers were finished, the top SiGe layer with the thickness of
200nm was deposited at 500°C. The deposition quality, thin film structure and residual strain in the film were
characterized by high-resolution X-ray diffraction (HRXRD). We found that the surface morphology and crystal quality
of SiGe thin film can be improved obviously. It was shown that SiGe top layer was relaxed and smooth by comparing the
measured and simulated (004) rocking curves. The peak range and relative position of the SiGe epilayer with respect to
the Si substrate in high-resolution reciprocal space map(HRRSM) described clearly the high crystal quality and the
strains relaxation. The surface morphologies of thin films were also observed by atomic force microscopy (AFM). The
surface is very smooth with RMS less than 7 Å.
Highly (h00) oriented growth of SrTiO3 thin films on Si(100) substrates by RF magnetron sputtering and their optical properties
J. H. Ma,
J. H. Pin,
Z. M. Huang,
et al.
Show abstract
SrTiO3 (STO) thin films were grown on Si(100) substrates by RF magnetron sputtering. The substrate temperature was
found to be a crucial parameter to obtain the highly (h00) oriented growth. At the substrate temperature of 700 °C, STO
thin films with the (h00)-orientation parameter (αh00) of more than 93% were realized. Using vitreous silica as the
substrate, the optical properties of STO thin film prepared at 700 °C were investigated by transmittance measurements.
The fitting method was used to calculate the refractive index and the film thickness from the transparent region of the
transmittance spectra. The dispersion of the refractive index was studied by considering a single electronic oscillator
model. According to Tauc's law, the band gap of the film was found to be about 3.62 eV.
The role of ion-assisted deposition in PVD
Z. Q. Ma,
C. B. Feng,
X. Tang,
et al.
Show abstract
An optimal energy interval in ion-assisted deposition of high crystalline films is predicted in the modeling of ion
impacting on surface. The result is in good agreement with the presented experiments. The possible application of the
evaluation of ion role for the fabrication of potential thin film materials is expected.
Synthesis of ordered ZnO nanorod film on ITO substrate using hydrothermal method
X. Tang,
Z. Q. Ma,
W. G. Zhao,
et al.
Show abstract
By using low cost, low-temperature hydrothermal approach and spin-coating technique, well-aligned ZnO nanorods have
been successfully prepared on ITO substrates. The ITO substrate was pre-patterned with ZnO particles as a seed layer for
the subsequent nucleic hybridization. The intuitionistic crystallinity of oriented ZnO nanorod array was characterized by
scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. It is shown that the preferred
orientation growth of the wurtzite structure along (002) plane is easily obtained with the approach. The size of the ZnO
nanorods has been found to be dramatically dependent on the concentration of zinc content in the solution.
Effect of working pressure on the properties of Al2O3/MgF2 HR coatings prepared by electron beam evaporation
Show abstract
The effects of working pressure on the properties of 355nm Al2O3/MgF2 HR coatings were investigated. A series of
samples were deposited by electron beam evaporation using the same deposition process at different working pressure.
Transmittance of the HR coatings was measured by Lambda 900 spectrometer. Structure of the samples had been
characterized by X-ray diffraction (XRD).The stress was measured by viewing the substrate deformation before and after
coatings deposition using an optical interferometer, the stress results range from 223MPa to 315MPa. Laser-induced
damage threshold (LIDT) was measured by a 351 nm Nd:YAG laser with a pulse width of 7 ns, the LIDT results range
from 2.69 J/cm2 to 11.03 J/cm2 with the working pressure changing. It was found that working pressure has important
effects on the absorption, stress and LIDT of 355nm Al2O3/MgF2 HR coatings. (351nm, 7ns).The working pressure was
no clear effect on the crystalline structure of the HR coatings.
Study of the defects in GaN epitaxial films grown on sapphire by HVPE
Show abstract
In this paper, the defects in hexagonal GaN epitaxial layers grown on (0001) sapphire (Al2O3) substrates by HVPE with a
horizontal tube reactor had been studied. The GaN epitaxial layers were etched by means of defect-selective etching
(Orthodox etching in molten KOH). The samples were characterized by Scanning Electron Microscopy (SEM) and
Cathodoluminescence spectra (CL). From surface morphology and cross-sectional images, the defects could be divided
into various types: cracks, low angle grain boundary (LAGB), nano-pipes and dislocations. These different defects were
discussed. The cracks were proposed as related to the strain. And the strain could not only come from the lattice
mismatch and thermal mismatch between sapphire and GaN layer in their interface, but also from the HVPE growth
process. It was found that these screw, mixed and edge type dislocations formed small hexagonal pits after etching.
Some pits would be observed in the area near LAGB. Additionally, by CL mapping technique, some non-radiative
recombination centers without surface terminations could be probed optically.
PTFE nanocrystallines by oriented plasma polymerization at atmospheric pressure
Ying Guo,
Jing Zhang,
Jinzhou Xu,
et al.
Show abstract
PTFE nano-crystallines with different morphology and crystal structures were rapidly formed by an Atmospheric Plasma
Polymerization at room temperature without any catalysts or templates. Transmission electron microscopy (TEM) and
X-ray diffraction (XRD) results indicated single crystal phase of the nano-crystallines. Other characterization methods,
such as Polarization optical micrographs of the nanocrystallines at high temperatures showed their higher thermal
stability compared to the PTFE bulk polymers. The atmospheric oriented plasma polymerization can serve as a common
method for nanofabrication of many other single crystalline polymer systems.
Nano-particulate coating on cotton fabric through DBD
Ying Guo,
Jing Zhang,
Jinzhou Xu,
et al.
Show abstract
Plasma polymerization of fluorocarbon was processed through dielectric barrier discharge (DBD). A thin hydrophobic
film packed with nano-particulate structure was obtained on cotton fabric surface. The contact angle of the water and 1-bromonaphthalene on coated cotton fabric was 133° and 124° separately. The surface morphology of the coating was
observed through SEM (Scanning Electronic Microscope). It was found that cotton fabric surface was tightly adhered to
a thin film packed by nano-particles from 10nm to 200nm. This process showed potential applications in continuous
coating of textiles with functional nano-particulate polymers, but without changing their softness performance.
Fabrication and characterization of Si nanotip arrays for Si-based nano-devices
Show abstract
A simple and efficient technique for fabricating two-dimensional arrays of silicon nanotips by using electron beam
lithography (EBL) and reactive ion etching (RIE) was reported. For the RIE processes, two kind of reactive gases, CHF3
and SF6, were used as plasma etching source for Si. The experiment results indicate that the reactive ion etching
mechanism is different: the isotropic process for SF6 and anisotropic for CHF3. It is found that the mixed O2/SF6 plasma
etching can improve the properties of profile and surface of Si nanotips. Under the condition of ratio ~15%, the 10 nm
top size of Si nanotips was obtained.
Quantification of substrate cleanliness level based on thin film adhesion measurement
Y. Tsukamoto
Show abstract
A new criterion about substrate cleanliness level was established by an adhesion measurement for Al and Cu thin films
deposited onto both Si and quartz glass substrates cleaned by various methods, such as swab scouring, ultraviolet light
irradiation, and oxygen plasma ashing. The substrate surface contamination level was controlled by exposing the
substrate itself to low vacuum impregnated with rotary pump oil mists. The new criterion about the substrate cleanliness
level was somewhat different from the water wettability one. In the case of the UV irradiation, adhesion strength
increased with exposure time, and then a constant maximum value was kept. On the other hand, the excess oxygen
plasma ashing resulted in adhesion degradation due to the Si surface oxidation.
Fabrication kinetics and properties of Ni-based nano-arrays embedded in anodic Al2O3 film
Hao Yan,
Jiancheng Zhang,
Chenxia You,
et al.
Show abstract
By direct current electrodeposition technique combined with the anodic aluminum oxide films, Ni-based nano-arrays
were successfully performed. The structure was studied by X-ray diffraction and high-resolution transmission electron
microscopy with selected-area electron diffraction. Energy dispersive spectroscopy was used to prove the composition of
the prepared nanowires. The magnetic property curves of Ni-based nano-arrays were measured by a physical property
measurement system. According to electrochemical analysis, the growth kinetics of the nanowires was studied by
determining the relationship between the current and time under different parameters, such as electrolyte temperature and
electrodeposition voltage.
The effect of bias voltage on the morphology and wettability of plasma deposited titanium oxide films
Show abstract
Hydrophobic and hydrophilic films with titanium oxide inside were grown by radio frequency plasma enhanced
chemical vapor deposition (RF--PECVD) on glass substrates. Bias voltage was used as an assistant for the deposition
process. And a comparison was made between with and without the bias voltage. Titanium tetraisopropoxide (TTIP-Ti
(OC3H7)4) was used as the precursor compound. Film wettability was tested by water contact angle measurement
(CAM). The water contact angle (WAC) of the film deposited in plasma without biased voltage was greater than 145°,
while the WAC of the film deposited in plasma with biased voltage was less than 30°. The morphology of the deposited
films was observed by scanning electron microscope (SEM). It is found that the films grown without bias voltage were
covered with lots of nano grain and pores, but the surface of the films deposition with bias voltage was much dense. The
chemical structure and property of the deposited films were analyzed by Fourier-transformed infrared spectroscopy
(FTIR), while the plasma phase was investigated by optical emission spectroscopy (OES).
Influence of annealing temperature on microstructures and resistivity of FexAl1-x films
Shuichang Yang,
Zhijun Liao,
Zhenliang Liu,
et al.
Show abstract
In this paper, FeXAl1-X films have been deposited on silicon substrates using electron beam evaporation, which have been
not reported to prepare FeXAl1-X films before. Subsequently, the films were annealed in vacuum better than 3×10-4Pa for
1 hour at 100°C, 280°C, 330°C, 450°C and 500°C, respectively. Electrical resistivities of the samples were been
measured by four point probe, and microstructures of the samples were characterized by X-ray diffraction(XRD). The
results show that, the resistivity of films reduces gradually with increasing of the annealing temperature, and the
structure of films can be improved after annealing. In addition, the resistivity of film reduces gradually with increasing
thickness and comes closed to the that of bulk when the film thickness becomes thicker than 100nm.
The influence of the substrate temperature variation on FexAl1-x thin films deposition
Zhenliang Liu,
Zhijun Liao,
Shuichang Yang,
et al.
Show abstract
FexAl1-x thin films had been prepared on Si (100) substrates by electron beam evaporation. The substrate temperature was
varied from room temperature to 450°C at an interval of 100°C. The crystalline orientation of deposited FexAl1-x thin
films had been characterized by X-ray diffraction (XRD) and the thickness was measured by Atomic profiler. The results
show that the crystalline orientation of FexAl1-x thin films depends on the substrate temperature. The thin films are crystal
at different substrate temperatures. The deposition rate becomes bigger from 30°C to 250°C and smaller from 250°C to
450°C. The surface morphology of deposited FexAl1-x thin films had been investigated by atomic force microscopy
(AFM). The results show that the surface roughness increases with increasing the substrates temperature to 450°C.
Effect of LaNiO3 sol concentration on the structure and dielectric properties of Pb(Zr0.53Ti0.47)O3 thin films grown on LaNiO3 coated Ti substrates
Xiaoyan Yang,
Jinrong Cheng,
Shengwen Yu,
et al.
Show abstract
Ferroelectric Pb(Zr0.53Ti0.47)O3 (PZT) thin films were deposited on LaNiO3 (LNO) buffered metal substrates by sol-gel
method. The LNO buffer layer also prepared by sol-gel method serves as the template for growing PZT thin films with
preferred orientation. The LNO sol is the precursor to prepare the LNO buffer layer. With the decreasing of the LNO sol
concentration, the PZT films on LNO layer shows varying intensity of the XRD (100) and (110) orientation, as well as
variation of the structural and dielectric properties. The PZT thin films with good dielectric properties can be obtained on
LNO buffer layer with LNO-sol of 0.1mol/L.
Characteristics of the composite films formed by CdTe electrodeposited on the ordered porous Al2O3
Zhenwei Song,
Jiancheng Zhang,
Chenxia You,
et al.
Show abstract
The nanowire arrays containing two phases of CdTe and Te have been synthesized by direct-current (dc)
electrodeposition in anodic alumina membrane (AAM) at room temperature. The results of transmission electron
microscope (TEM) show the nanowire arrays have ordered diameters of about 60 nm, which corresponds to the pore size
of the AAM template we used. The selected area electron diffraction photo shows the nanowire arrays have the mixture
structure of single crystal and polycrystalline. The growth mechanism of the nanowire arrays is also suggested.
Characteristic of ZnO films prepared by the sol-gel process
Guannan He,
Bo Huang,
Suntao Wu,
et al.
Show abstract
ZnO thin films with or without Al doping were grown on the glass substrates by sol-gel method and subsequently
annealing treatments at high temperatures were performed to optimize films' morphologies and properties. The crystal
structures of ZnO films were characterized by X-ray diffraction (XRD), and XRD spectra show a shift of (002)
diffraction peak to the higher 2θ values with changing the Al-doping concentration. Optical transmittance spectrums
exhibit a sharp absorption edge at around 380nm undergoing a blue shift induced by aluminum doping. An apparent
particle size decreasing was displayed by scanning electron microscopy (SEM) images with the Al-doping concentration
increasing.
Voltage-controlled change of MIS reflectivity in visible and near infrared band
Show abstract
Voltage-induced reflective changes of Pt/BLT/Si and Pt/STO/Si are investigated in visible and near infrared band. A
theoretic calculation of inversion layer plasmons is set up. The most sensitive optical band and the voltage value interval
causing fastest change rate are indicated. Some variance regularities are described, and this study provides the basically
theoretical support for the application of an optical readout infrared imaging device: MFIS.
Crystallization of manganese cobalt nickelate films prepared by chemical deposition
Yujian Ge,
Zhiming Huang,
Yun Hou,
et al.
Show abstract
Manganese cobalt nickelate films (MnxCoyNi3-x-y)O4 (MCN) are successfully prepared by chemical deposition method
at a crystallization temperature of 600°C, which is greatly reduced from the traditional sintered temperature of ~1050 -
1200°C. From the XRD and AFM, we find the grain size of the MCN films increases from 20 to 60 nm with the
annealing temperature increase from 600°C to 900°C.
The structural and electrochemical properties of tin oxide films prepared by RF magnetron sputtering
Minzhen Cai,
Jie Song,
Liangtang Zhang,
et al.
Show abstract
Tin oxide thin films have been deposited on oxide silicon substrates using a RF magnetron sputtering process with
various sputtering power. The crystal structures of the tin oxide thin films were characterized and analyzed by X-ray
diffraction. The surface morphology of the films were observed by SEM. The electrochemical properties of the films
were also tested by constant current charge and discharge cycle tests. The results of XRD indicate that all the films are
crystalline. The results of SEM exhibit that the grain size of surface expands as sputtering power rises.
Study of final polishing slurry for silicon substrate in ULSI
Weiguo Di,
Ming Yang,
Yuling Liu
Show abstract
Based on the analysis of mechanism of silicon polishing, this paper discusses the influence of the final polishing slurry
on polishing quality. The selection of components in the final polishing slurry is discussed. The abrasive of small size is
used to reduce the surface roughness. The alkali without sodium ions is selected to reduce metal ions pollution. The
relation between adsorption mechanism and the surfactant is analyzed. As a result, the nonsodium final polishing slurry
with small particle size, high polishing rate and high quality is realized.
Substrate effect on the growth and thermal electrical properties of vanadium oxide thin films
Show abstract
Vanadium oxide (VOx) thin films were deposited on different substrates by reactive DC magnetron sputtering. Silicon
substrate, Si3N4/Si substrate, glass substrate, and α-Al2O3 substrate were adopted in experiments. Results revealed that
the structural features of VOx thin films strongly depend on the substrates. Analysis of square resistance and its
temperature dependence demonstrated that the crystal structure and the growth mode of VOx films play important roles
in the film electrical properties. Experiments demonstrated that substrates have great influence on the growth mode and
thermal resistance properties of VOx thin films.
Influence of substrate temperature on the morphology and thermal resistance of vanadium oxide thin films
Show abstract
The dependence of morphology and thermal resistance on the substrate temperature during the deposition of the
vanadium oxide thin films (VOx) was studied. Atomic-force microscopy (AFM) analysis results revealed that the
structural features of VOx thin films strongly depend on the substrate temperature. Analysis of square resistance and its
temperature dependence demonstrated that the difference of morphology introduced by substrate temperature plays an
important role on the electrical properties of the films. The width of the thermal resistance hysteresis loop was also
observed varied with the substrate temperature.
Properties of homoepitaxial 4H-SiC and characteristics of Ti/4H-SiC Schottky barrier diodes
G. Chen,
Z. Y. Li,
S. Bai,
et al.
Show abstract
This paper describes the properties of the homoepitaxial 4H-SiC layer, the fabrication and electrical parameters of
Ti/4H-SiC Schottky barrier diode (SBD). The 4H-SiC epitaxial layers, grown on the commercially available 8°off-oriented
Si-face(0001) single-crystal 4H-SiC wafers, have been performed at 1550~1600°C by using the step controlled
epitaxy with low pressure chemical vapor deposition. X-ray diffraction measurement result indicates the single crystal
nature of the epilayer, and Raman spectrum shows the typical 4H-SiC feature peaks. When the off-oriented angle of
substrate is 8°, the epitaxial growth perfectly replicates the substrate's polytype. High quality 4H-SiC epilayer has been
generated on the 4H-SiC substrate. Ti/4H-SiC SBDs with blocking voltage 1kV have been made on an undoped epilayer
with 12um in thick and 3×1015cm-3 in carrier density. The ideality factor n=1.16 and the effective barrier height φe=0.9V
of the Ti/4H-SiC SBDs are measured with method of forward density-voltage (J-V). The diode rectification ratio of
forward to reverse (defined at ±1V) is over 107 at room temperature. By using B+ implantation, an amorphous layer as
the edge termination is formed. The SBDs have on-state current density of 200A/cm2 at a forward voltage drop of about
2V. The specific on-resistance for the rectifier is found to be as 6.6mΩ•cm2.
CVD growth of Ge films on graded Si1-xGex: C buffers
R. H. Wang,
P. Han,
Q. Mei,
et al.
Show abstract
Ge films have been deposited on Si (100) substrates with graded Si1-xGex:C buffers by chemical vapor deposition (CVD)
method. Based on the Auger electron spectroscopy result, a growth model for the buffers has been proposed, in which
the buffers are thought to be composed of two layers. One is the Si1-xGex:C epilayer due to the reaction of GeH4, C2H4
and Si atoms diffusing up from the substrate, and the other is the Si1-xGex layer due to the reaction of Si and Ge atoms
diffusing down from the Si1-xGex:C epilayer. The energy dispersive spectroscopy result indicates that Ge atoms diffuse
further when the growth temperature is higher, demonstrating the growth model indirectly. With the graded buffers,
epitaxial Ge films show the perfect crystalline quality, and the excellent transport property with the electron mobility
approaching that of bulk Ge materials at the same doping level.
MOCVD growth and annealing characteristics of Mg-doped AlGaN films
J. Yao,
P. Han,
Z. L. Xie,
et al.
Show abstract
We investigate the growth of Mg doped AlxGa1-xN films grown by metal organic chemical vapor deposition (MOCVD).
The high temperature AlN interlayer can improve the quality of films, reducing the density of dislocations. With the
increase of Al composition, the quality of films dramatically decreases, and a large number of island-shaped crystal
nuclei can be observed, for three-dimensional growth mode of Mg-doped AlxGa1-xN can not be transformed into two-dimensional
mode easily. Both the increase of Al composition and Cp2Mg flux can increase the density of screw
dislocations. The increase of Cp2Mg flux can considerably increase the density of edge dislocations, while the increasing
Al composition has little impact on the density of edge dislocations. Finally, annealing at 900°C for 15 minutes after
growth is the ideal annealing condition for obtaining p-type Al0.2Ga0.8N, with hole concentration of 1.0×1017 cm-3.
The study of ZnO thin film fabricated by low temperature wet chemical method and its optical properties
Shengbo Wu,
Wenbin Sang,
Bin Wang,
et al.
Show abstract
The optical properties of the nano-ZnO thin films were studied, which were prepared by low temperature wet chemical-method
combined with ultrasonic treatment. The thin film could emit the strong UV and blue light. The blue emission
was caught by the interstitial zinc (Zni), which could be confirmed by Raman spectrum. The relationship of the optical
properties and processing parameters was also discussed. The reaction temperature, the reaction time and the different
molar ratios of Zn2+ to TEA could affect on the intensities of the UV emission and the blue emission of the ZnO thin
film, respectively. The mechanism of the phenomena was brought forward by analyzing the FTIR spectrum.
Study of Si/SiO2 hybrid antireflective coatings on SLD prepared by DSEBET
M. X. Sun,
M. Q. Tan,
M. Zhao
Show abstract
We introduce a double source electron beam evaporation (DSEBET) technique in this paper. The refractive index
coatings were fabricated on K9 glass substrate by adjusting the evaporation rates of two independent sources. The
coatings, which were described by atomic force microscopy (AFM), show good compactness and homogeneity. The
antireflective (AR) coatings were fabricated on Superluminescent Diodes (SLD) by DSEBET. The hybrid AR coatings
on the facets of SLD were prepared in evaporation rates of 0.22nm/s and 0.75nm/s for silicon and silicon dioxide,
respectively. The results of AFM and spectral performance of coated SLD show that DSEBET has a promising future in
preparing the coatings on optoelectronic devices.
Simulation of SiC deposition in a hot wall CVD reactor
Wei Jia,
Yuming Zhang,
Yimen Zhang,
et al.
Show abstract
The present study focuses on the numerical study of 4H-SiC film deposition on a horizontally 4H-SiC substrate with H2
as the carrier gas and C3H8 and SiH4 as precursors in low pressure using a hot wall CVD reactor. The growth rate along
the susceptor is calculated. The effect of inlet C/Si ratio on the growth rate is investigated. Among the reacting species
C2H2, CH3SiH2SiH, Si and SiH2 contribute most to growth.
Wurtzite structure high Mg content ZnMgO thin films deposited by oxygen-plasma enhanced pulsed laser deposition
Yanfei Gu,
Xiaomin Li,
J. F. Kong,
et al.
Show abstract
Wurtzite structure ZnMgO thin films with the energy gap (Eg) of 4.2 eV were deposited by oxygen-plasma enhanced
pulsed laser deposition (PEPLD) on quartz glass. Oxygen-plasma increases the Zn content in ZnMgO thin film, which
induced the evolution from cubic to hexagonal structure. The effects of target-substrate (T-S) distance on the band gap
and crystal quality of ZnMgO thin film deposited by PEPLD were studied by transmittance spectra and Raman. The
band gap of ZnMgO increased from 3.84 eV to 4.03 eV and the crystal quality decrease gradually when the T-S distance
decreased from 9 cm to 5 cm.
Thick and adherent (cBN/nano-diamond)3 multilayer films deposited by RF magnetron sputtering
Show abstract
Using physical vapor deposition (PVD) method, the (cBN/nano-diamond)3 multilayer film with phase purity, high
hardness and low residual stress was synthesized on silicon substrates supported by a thick nano-diamond buffer. This
method presented is characteristic with the direct cBN growth on diamond without soft, non-cubic BN interface layers;
the synthesis of multilayer films with extraordinary adhesion to the substrates and higher hardness than a cBN single
film, and the stress of the multilayer film can be reduced to only one forth of that of a cBN single film. These prime
technological properties open the route to the mechanical exploitation of cBN films.
The properties of ZnO thin films fabricated by ion beam sputtering and RF magnetron sputtering
Show abstract
ZnO thin films were prepared by two methods .One was ion beam sputtering then annealing at 700°C in O2, another was
RF magnetron sputtering then annealing at 600°C in O2. The structures, morphologies, and electrical resistivities of the
ZnO films prepared by two methods were investigated and compared. The influences of two different methods on
properties of ZnO thin film were studied by XRD, AFM and LCR HITESTER. Compared with RF magnetron sputtering,
the ZnO films fabricated by ion beam sputtering deposition have disordered growth orientation, bigger surface roughness
and higher electrical resistivity.
Photocurrent generated by nanometer silicon crystallites
Show abstract
We report on the photocurrent generated by nanometer grains embedded in hydrogenated amorphous silicon (a-Si:H), i.e.,
the hydrogenated nanocrystalline silicon (nc-Si:H) thin film. The embedded nanometer grains within the a-Si:H
boundaries are found to be a narrow continuous energy band in the a-Si:H band-gap, from which the transitions can
effectively generate the free electron-hole pairs, resulting in the observed high photocurrent. The high density of
nanometer Si crystals is a good means to improve the photo current response, and the fabrication of the low-cost infrared
photo detector by a single layer of nc-Si:H thin film on glass substrates is also expected.
MOCVD growth of GaN films on Si-rich SiNx nanoislands patterned sapphire
Zhilai Fang,
Shuping Li,
Junyong Kang
Show abstract
We intentionally patterned Si-rich SiNx nanoislands on sapphire substrates and found the SiNx significantly influenced
the subsequent growth of GaN films. Distinct GaN islands of triangular base were formed caused by the enhanced
diffusion and regrowth anisotropy during the annealing processes of GaN nucleation layers. Subsequent growth of GaN
epilayers at high temperature with initial low V/III ratios on the nucleated triangular islands resulted in island coarsening
and shape variations from triangular to hexagonal due to the dominating gas phase transport growth mechanism and
limited diffusion length. Further growth with high V/III ratios eventually resulted in layer-growth with surface roughness
of ~2.6 Å. Both AFM and XRD results showed a significant improvement of the crystalline qualities with estimated
threading dislocation (TD) density of about 1×108 cm-2 when Si-rich SiNx nanoislands patterning was performed.
Photoluminescence measurements showed that the yellow and blue emissions were substantially suppressed.
Study of the electrodeposition of self-assembled ZnO-surfactant hybrid thin films
Xiaoyan Gan,
Xiangdong Gao,
Xiaomin Li
Show abstract
Well-defined lamellar-structured ZnO-SDS hybrid thin films were grown on ITO glass from zinc nitrate solution
containing anionic surfactant sodium dodecyle sulfanate (SDS) via the potentiostatic electrodeposition route. The effect
of deposition potentials on the self-assembly process at the interface was discussed. Results show that the period of the
lamellar structure doesn't have obious dependance on the deposition potential. However, the quality of lamellar
structures incorporated in the ZnO films can be enhanced as the deposition potential increases. Optical analysis showed
that the hybrid films had good optical qualities, and their optical transmittance decreased as the deposition potential
increased.
Characterization of (001)-orientated polycrystalline a-HgI2 films grown by hot wall physical vapor deposition
Yaoming Zheng,
Weimin Shi,
Guangpu Wei,
et al.
Show abstract
The highly (001)-orientated α-HgI2 film was deposited by hot wall physical vapor deposition (HWPVD) technology.
The scanning electron microscopy (SEM), X-ray diffraction (XRD), dark current versus applied voltage and capacitance-frequency
characteristics analysis showed that the film was compactly formed by separated columnar monocrystallines
with uniform orientation along c-direction and with high resistivity (2.5×1012Ω•cm) and low dark current.
Preparation of polycrystalline HgI2 films by PVD method under ultrasonic wave
Yaoming Zheng,
Weimin Shi,
Guangpu Wei,
et al.
Show abstract
Highly oriented polycrystalline α-HgI2 thick films are fabricated by physical vapor deposition method under the
conditions of 59KHz ultrasonic wave and relatively lower source temperature of 80°C. The ultrasonic wave is used in the
process of physical vapor deposition films preparation for the first time. With the effect of ultrasonic wave, the film
quality and the growth rate can be obviously improved. The growth mechanism as well as impacts of ultrasonic wave is
also discussed.
Investigation of nanostructure on silicon by electrochemical etching
Show abstract
Fabrication of deep pores and trenches in nano-size will enable the embedded nanodevice integrated with silicon IC.
However, the conventional dry etching method needs very expensive equipment and the process is quite complicated.
Recently, electrochemical etching was developed to fabricate structures with high aspect ratio. Anodization was
performed in a solution of HF with certain concentration mixed with ethanol by 1:1 in volume. The backside of the wafer
was illuminated by a halogen lamp. The whole etching system was monitored by a computer system. It is found, in case
of etching in a low current with 5%HF electrolyte, the size etched pores can be less than 100 nm. However, the deep
trench structures becomes a line array of pores. Further work is in progress to investigate the detail.
Mechanics analysis of the multi-point-load process for the thin film solar cell
Zhiming Wang,
Guangpu Wei,
Zhengbang Gong
Show abstract
The main element of thin film solar cell is silicon. Because of the special mechanical characteristic of silicon, the method
of loading pressure on the thin film solar cell and the value of pressure is the key problem which must be solved during
the manufacturing of thin film solar cell. This paper describes the special mechanical characteristic of silicon, discussed
the test method overall; value of pressure on thin film solar cell; the elements and the method of load by ANSYS finite
element, according to these theory analysis, we obtained the key conclusion in the actual operation, these result have a
great meaning in industry.
Applications of Thin Films
Photon upconversion devices for imaging
Show abstract
This paper reviews our research on photon upconversion devices for wavelengths from 1.5 μm to 0.87 μm. The 1.5 μm is
chosen for its importance for eye-safe active imaging; whereas 0.87 μm corresponds to the bandgap of GaAs which is the
active region of our high efficiency light emitting diode (LED). The basic idea is to integrate a 1.5 μm detector with a 0.87
µm LED, connected in series. The detected photocurrent drives the LED, thereby achieving the upconversion. Various
approaches of integration methods and device designs have been tested. The upconversion approach provides an alternative
to the standard hybrid integration with readout circuits and may be advantageous for some applications.
Ultraviolet-to-infrared dual-band detectors based on quantum dot and heterojunction structures
Show abstract
Tunneling quantum dot photodetector (T-QDIP) structures designed for multi-band infrared and heterojunction detectors for
ultraviolet (UV) to infrared (IR) radiation detection are presented. In T-QDIPs, photoabsorption takes place in InGaAs QDs
due to intersubband transitions of carriers. Photoexcited carriers are selectively collected through resonant tunneling, while
the dark current is blocked by AlGaAs/InGaAs tunneling barriers. This approach to block dark current without reducing
photocurrent was observed in a detector responding at ~ 6 and ~ 17 μm up to 300 K. In addition, UV/IR dual-band detectors
were developed based on GaN/AlGaN Heterojunction Interfacial Workfunction Internal Photoemission (HEIWIP) structures.
A typical HEIWIP detector structure consists of a single (or series of) doped emitter(s) followed by an undoped barrier(s)
between two highly doped contact layers. Reported UV/IR structures use n-doped GaN emitters and AlxGa1-xN barriers. The
UV response is due to interband (valence-to-conduction) transitions in the undoped AlGaN barrier, while the IR response
arises from intraband transitions in the n-doped GaN emitter. Preliminary detectors were successfully demonstrated with a
360 nm threshold UV response up to 300 K and 8-14 μm IR response up to 80 K.
Extreme ultraviolet multilayer mirrors for astronomical observation
Show abstract
Multilayer mirrors are the important optical elements for astronomical observation at extreme ultraviolet region. In this
article, three kinds of multilayer mirrors were introduced for solar observation and magnetosphere observation. Mo/Si
multilayer mirror was fabricated for solar Fe-XII emission line at wavelength of 19.5nm. For solar He-II radiation at 30.4
nm, Mo/Si, Si/SiC, Si/C, Si/B4C and Mg/SiC multilayers were investigated, and the measurements results shows that
Mg/SiC multilayer provides the highest reflectivity of 43.8% at incidence angle of 5 degree. The third multilayer mirror
was a dual-function mirror used for earth's magnetosphere observation, which requires high-reflective for He-II emission
line at wavelength of 30.4nm but anti-reflectance at 58.4nm from ionosphere He-I emission. Using aperiodic Mg/SiC
multilayer, the dual-function multilayer mirror was designed. Compared to periodic multilayer, the dual-function
multilayer suppresses the reflectivity for He-I at 58.4nm from 2.2% to 0.1%, without loss of the reflection for He-II at
30.4nm, significantly.
Surface properties and field emission of BN and BCN films
Takashi Sugino,
Chiharu Kimura,
Hidemitsu Aoki
Show abstract
Synthesis of boron nitride (BN) and boron carbon nitride (BCN) films is carried out by plasma-assisted chemical vapor
deposition. The electron affinity of the BN and BCN films is estimated from the threshold energy of the photoelectron
yield and the bandgap energy. The negative electron affinity appears on the BN surface, while the positive electron
affinity increases on the BCN surface with increasing C composition ratio. It is found that a reduction in the electron
affinity occurs due to N2 plasma treatment rather than H2 plasma treatment for the BCN film. Field emission
characteristics of the BN and BCN nanofilms are investigated. The turn-on electric field of the electron emission does
not increase in the region of the C composition ratio lower than 20 %. This is due to the effects of increasing electron
affinity and decreasing conduction band discontinuity between the BCN nanofilm and Si substrate. It is demonstrated
that field emission characteristics of the graphite nanofiber are improved significantly by coating with BN nanofilm.
High-performance AlGaN-GaN HEMT materials and devices grown and fabricated on Si substrates
Z. H. Feng,
J. Y. Yin,
F. P. Yuan,
et al.
Show abstract
Crack-free AlGaN-GaN HEMT materials with 1.2-μm-thick were grown on high-resistivity Si(111) substrates by
MOCVD. The sample showed a high 2DEG mobility, 1350cm2/V•s at 300K and 5900cm2/V•s at 77K, respectively. High
optical and structural qualities were confirmed by PL and XRD. The dc and rf characteristics of AlGaN-GaN microwave
power devices with 0.4μm gate length and 1mm of the gate width were probed. The saturated drain current density was
around 0.8A/mm, and the peak transconductance was beyond 230mS/mm. Tunning for a maximum output power of
5.1W, a gain of 9.1dB and a peak power-added efficiency (PAE) of 35% was obtained, respectively.
Single dipole mode photonic crystal laser on InGaAsP/InP QW waveguide slab
Wanhua Zheng,
Minxin Xing,
Gang Ren,
et al.
Show abstract
Single point defect microcavity possesses only the degenerate dipole modes under certain photonic crystal structure
parameters. By deforming lattice structure, the degeneracy of the dipole modes has been broken. Theoretical simulation
shows the large splitting of 65nm between the splitted x-mode and y-mode, approximate to the luminescent gain
spectrum, which benefits for the single mode lasing. Experimentally the single dipole mode lasing, y-mode, is achieved
in the deformed microcavity.
Mode analysis of photonic crystal polarization beam splitter and its application in integrated circuits design
Show abstract
In this work, the guided modes of a photonic crystal polarization beam splitter (PC-PBS) are studied. We demonstrate
that the transmission of a low-loss photonic crystal 120° waveguide bend integrated with the PBS will be influenced if
the PBS is multi-moded. We propose a single-moded PC-PBS structure by introducing deformed structures, and it shows
twice the enhancement of the transmission. This device with remarkable improvement of performance is promising in
the use of photonic crystal integrated circuits design.
The whispering gallery mode in photonic crystal ring cavity
Show abstract
Whispering gallery modes (WGMs) in microcavities possess ultra- high cavity Q factor. Such microcavity are easy to be
fabricated, so WGMs have attracted much attention in the area of photonics and integrated photonic circuits. It is well
known that the effect of total internal reflection restricts the size of this mirocavity. Such drawback goes against the
integration of photon. However, the photonic crystal microcavities (PCMC) make a breakthrough recently. The WGMs
in the PCMC are possible to gain both ultra-high Q and ultra-small mode volume. In this paper, the property of the mode
in photonic crystal ring cavity is analyzed by FDTD and PWE. By modifying the airholes in the corners of the ring
cavity, we can obtain the WGM. Also the Q factor of WGM in photonic crystal ring cavity is calculated. This favors the
design of the photonic crystal microcavity components.
Effects of oxygen partial pressure on the resistance switching properties of La0.7Ca0.3MnO3 thin films prepared by pulsed laser deposition method
Weidong Yu,
Xiaomin Li,
Feng Wu,
et al.
Show abstract
The La0.7Ca0.3MnO3 (LCMO) films were prepared by the pulse laser deposition method on Pt/Ti/SiO2 /Si substrates under the
O2 partial pressures of 0.01Pa, 1Pa, and 10 Pa, respectively. XRD patterns show that LCMO film grown under the O2 partial
pressure of 0.01Pa exhibited good crystallinity and (110) preferred orientation. Due to the strong collision in the plume, the
crystal quality of LCMO films grown under 1Pa and 10Pa decreased remarkably. Electrical measurements show that the
LCMO films grown under low O2 partial pressure has stable resistance switching property. The oxygen content but
crystallinity is a key factor for the resistance switching property of LCMO film. The lack of oxygen promotes the resistance
switching properties of LCMO films.
Preparation of Pd doped WO3 films via sol-gel method and their gasochromic properties
Show abstract
In this paper, WO3 sol was prepared via the sol-gel method, and palladium chloride powder was dissolved in the sol in
different W: Pd molar ratios. Pd doped WO3 films were coated on silicon wafers and ordinary slide glasses by
dip-coating method. The grain distribution of WO3 sol doped with PdCl2 was measured by Laser Particle Size Analyzer.
Surface morphology and microstructure of WO3 films which doped or undoped with PdCl2 were analyzed by AFM,
which show that PdCl2 has an important effect on the structure of the WO3 films. The gasochromic properties of the films
are investigated by UV-Vis spectrophotometer. The WO3 films show good gasochromic properties. The effect of
concentration of PdCl2 on gasochromic kinetic process of WO3 films was investigated. Finally the modulation of the
light transmittance by the gasochromic films was discussed.
Coherent amplification by multilayer nematic liquid crystal cell
Show abstract
Beam coupling theory for the nonlocal Raman-Nath gratings was developed, which showed that the gain initially
increased exponentially with the sample thickness, then deviated from the exponential relation and lowered gradually. It
was predicted that large thickness and high intensity sensitivity were simultaneously necessary for the sample to obtain
larger gain. The quantitative relation between the signal gain and the sample thickness was investigated experimentally
by using a multilayer photorefractive liquid crystal structure to increase the overall interaction length, and the
experimental result fitted the theory nicely.
Study on the photoinduced current in nematic liquid crystal cell with alkanethiol self-assembled monolayer
Show abstract
In this paper we constructed nematic liquid crystal (NLC) cells with the gold film as one substrate as well as the cells
with the gold film covered with decanethiol and hexadecanethiol self-assembled monolayers (SAMs). We found the
photocurrents in these three kinds of cells all increased linearly with the power of the 632.8nm illuminating beam. And
the existence of alkanethiol SAM or application a high voltage could enhance the growth rate of the above linear
relations. These indicated that the current originated from the light induced carrier injection from the gold electrode to
NLC film, and a model of photocurrent limited by near-electrode excitons was introduced to explain the photoinduced
carrier injection.
Multi-layer antireflection coatings for silicon solar cells using a sol-gel technique
B. B. Shi,
Z. Q. Ma,
X. Tang,
et al.
Show abstract
In order to improve the opto-electronic conversion efficiency of solar cells, antireflection coatings (ARCs) have been drew a
great attention for the application in the terrene. Generally, the coating is obtained by vacuum processing such as thermal
evaporation, reactive sputtering and plasma-enhanced chemical vapor deposition (PECVD). In this work, multi-layer
antireflection coatings have been performed by a modified sol-gel technique, which is low-cost and simple. The multi-layer
films consisted of SiO2 and TiO2. The physical phase and morphology of each layer were characterized by atomic force
microscopy (AFM). The TiO2 single-layer and SiO2/TiO2 double-layer antireflection coatings were respectively annealed at
150°C, 350°C and 550°C. The sols of TiO2 and SiO2 were aged for 24 hours and then were spin coated on the Si substrate. It
was found that the reflectance of double-layer ARCs was generally lower than that of single-layer ones. The reflectance of
films without being aged was lower than that of sols were aged for 24 hours. In all samples, the SiO2/TiO2 double-layer film
which was annealed at 150°C and which sols were not aged for 24 hours had the lowest reflectance.
Research of a diamond-like carbon (DLC) films: promising candidate for absorber layer of solar cells
Show abstract
In this paper, successful fabrication of DLC thin films with tunable band gaps deposited by r.f. plasma-enhanced
chemical vapor deposition (RF-PECVD) under different bias voltages is reported. By Ultraviolet Transmission
Spectroscopy, it is revealed that the band gaps vary from 1.0eV to 2.1eV, which can cover the most important part of the
solar spectrum for terrestrial application solar cells. And the mechanism that band gaps of DLC films varied with the bias
voltages was analyzed by X-ray Photoelectron Spectroscopy (XPS). It is gotten that the different ratio of sp2/sp3 results
in different band gaps, which is apparently resulted by different bias voltage during the deposition process. The band gap
tends to have higher value at less sp2 content. The experiment results show that DLC multi-layer films can be used as an
effective absorber layer for thin films solar cells.
Ohmic contacts with heterojunction structure to N-type 4H-silicon carbide by N+ polysilicon film
Show abstract
The polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM (Transfer Length Method) test patterns
with polysilicon structure are formed on N-wells created by phosphorus ion (P+) implantation into Si-faced p-type 4H-SiC
epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition (LPCVD) and doped by
phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/square The specific contact
resistance ρc of n+ polysilicon contact to n-type 4H-SiC as low as 3.82×10-5Ωcm2 is achieved. The result for sheet
resistance Rsh of the P+ implanted layers in SiC is about 4.9kΩ/square. The mechanisms for n+ polysilicon ohmic contact to ntype
SiC are discussed.
Tunable microwave band-stop filters using ferromagnetic resonance
Baolin Zhao,
Yu Shi,
Hui Zhong,
et al.
Show abstract
In this paper, we present some results on FeCoB-based microwave band-stop filters. These structures, prepared on GaAs
substrates, are compatible in size and growth process with on-chip high-frequency electronics. The band-stop filters have
been realized with microstrips which incorporate ferromagnetic and dielectric layers to absorb microwave energy at the
ferromagnetic resonance (FMR) frequency. The absorption notch in transmission can be tuned to various frequencies by
varying an external applied magnitic field. For our devices, which incorporate FeCoB as the ferromagnetic material, the
resultant FMR frequencies range from 12-22 GHz for applied fields up to only 1000 Oe. Comparatively, the frequency
range of those devices using permalloy and Fe is substantially lower than FeCoB-based devices for applied the same
fields. We constructed devices using monocrystalline FeCoB films grown in a sputtering system. Our devices are of
different construction than other dielectric microstrips and show much improvement in terms of notch width and depth.
The maximum attenuations of 3.5 dB/cm and 90dB/cm are observed respectively in two different structures.
Design and properties of STW resonators on AT-quartz
Hualei Wang,
Yu Shi,
Hui Zhong,
et al.
Show abstract
Surface transverse waves (STW) resonators exhibit substantial advantages over conventional surface acoustic wave
(SAW) resonators without further demands for new materials or improved design and technology. They demonstrate
higher operating frequencies, better temperature stability, higher intrinsic material quality and etc. In this work, the low
loss and high quality factor STW with center frequency at 421 MHz fabricated with a line width of 3 μm were uniquely
designed and fabricated on AT quartz substrate. The insertion loss of the device was as low as 2 dB, and the loaded
quality factor was as high as 1000. Insertion losses as function of structure parameters are discussed.
Research on the realization of high precision RC array through IC thin film technology
Show abstract
This paper discusses some advantages of IC thin film technology in realizing RC array that traditional thick film
technology does not have, which make IC thin film technology the mainstream in realizing RC array devices. Then it
focuses on how to use IC thin film technology to realize high precision RC array, some practical techniques are put
forward, based on our experiments and experience in layout design and fabrication. These techniques are demonstrated
separately according to the respective characteristics of resistor and capacitor. Finally, the different ranges of precision of
the devices tested in different ways through specific experiments are given.
Photovoltaic properties of near-infrared absorbing manganese (II) phthalocyanine sensitized mesoporous TiO2 films
Fei Zheng,
Yue Shen,
Feng Gu,
et al.
Show abstract
Mesoporous TiO2 particles were prepared and characterized by X-ray diffraction (XRD) and high resolution transmission
electron microscopy (HRTEM), which confirmed that well-organized mesostructure has been formed. Near-infrared
absorbing tetra-amino manganese (II) phthalocyanine (TAMnPc) was synthesized and employed as sensitizer and
TAMnPc sensitized mesoporous TiO2 (TAMnPc-TiO2) films were prepared and characterized by electronic absorption
spectrum. Compared with bare TiO2 films, TAMnPc-TiO2 films exhibit an additional Q absorption band in near-infrared
region. Current-voltage (I-V) characteristics of TAMnPc-TiO2 films in dark and under irradiation were tested.
Adsorption of TAMnPc onto mesoporous TiO2 leads to a significant rise in photoconductivity.
The heterojunction structure of n-Si/p-nanocrystalline diamond film for UV detection
Show abstract
A heterostructure of nanocrystalline diamond film / n-Si was fabricated successfully, where the un-doped p-type
nanocrystalline diamond (NCD) film was grown by an electron assisted hot filament chemical vapor deposition (EA-HFCVD)
technology. The structure and morphology of the NCD film were analyzed by Raman spectroscopy, X-ray
diffraction (XRD) and scanning electron microscopy (SEM). I-V characteristic of the p-NCD/n-Si heterojunction
indicated that this structure was rectifying in nature with a turn-on voltage of ~0.5V. The p-NCD/n-Si heterostructure
was also used for UV detector applications. Operating at a bias voltage of 10V, this photodetector showed a significant
discrimination between UV and visible light, and the UV/visible-blind ratio was about three orders of magnitude.
Electrical properties of radiation detector based on polycrystalline mercuric iodide (HgI2) thick film
Weimin Shi,
Yaoming Zheng,
Yuying Guo,
et al.
Show abstract
Potentially low cost and large area polycrystalline mercuric Iodide (HgI2) is one of the preferred materials for the
fabrication of room temperature X-ray and gamma-ray detectors. In this paper, the technique of fabricating
polycrystalline HgI2 detectors was studied and the energy resolution of 13.1% for 5.5 MeV 241Am α particles at room
temperature was obtained for the first time. The optimal choice of particle injecting from negative interface enhances the
collection efficiency.
Fabrication and characterization of 3D pn junction structure for radiation detection
Show abstract
In this report, p-type macroporous silicon has been prepared by anodization. A phosphorus diffusion step is employed for
the formation of three dimensional pn junction structures on this macroporous silicon. I-V and C-V measurement were
employed to characterize the electrical properties. The results were compared with numeric simulation with T-SUPREM4
and MEDICI. It has been demonstrated that three-dimensional structure can increase the effective junction
area and the collective efficiency remarkably, and hence improve the performance of semiconductor radiation detector.
A beam operated MEMS variable optical attenuator
Shuqin Ding,
Xiaodong Zhang,
Xiaoming Chen,
et al.
Show abstract
The microelectromechanical variable optical attenuator (VOA) using an electrostatic beam combined with a fiber-optic
collimator has designed and fabricated. This VOA is based on silicon-on-insulator (SOI). When the driving voltage is
applied to the beam and the substrate, the beam will yield a vertical displacement. Then the reflected light can't enter
into the coupled fiber completely. Based on electrostatic actuation, the attenuation level is adjusted by changing the
displacement of the beam. The relationship between the voltage and the displacement was analyzed by using ANSYS, a
finite element analysis software package. The result of the simulation shows that the attenuator with the new structure
has good performances. The fabrication steps use two wet etching processes. The active layer of SOI wafer is first
patterned into the mirror sharp by TMAH, and the backside is etched to the buried oxide (BOX) using a 2-μm-thick SiO2
mask. After releasing the structure in hydrofluoric acid, gold layers are deposited by vacuum evaporation. The testing is
still in progress.
Surface modified polysiloxane a sensitive coatings for QCM sensors
Zhihua Ying,
Yadong Jiang,
Xiaosong Du,
et al.
Show abstract
A quartz crystal microbalance (QCM) gas sensor with polysiloxane sensing film was fabricated for detection of dimethyl
methyl phosphonate (DMMP), the simulant of chemical warfare agents (CWAs). Poly(methyl-3,3,3-trifluoropropylsiloxane) (PMTFPS) was oxygen plasma treated and then grafted with sulfosalicylic acid (SSA). The
resultant SSA modified PMTFPS (SMP) was drop-coated on the electrode of QCM. Compared with the PMTFPS-QCM
and SSA-QCM sensors, the sensitivity of SMP-QCM sensor was much higher. However, the SMP films showed less
resistance to humidity variations. The selectivity of SMP-QCM sensor to DMMP was also investigated, and better results
was showed out after SSA grafted.
Comparative NH3-sensing characteristic studies of PANI/TiO2 nanocomposite thin films doped with different acids
Huiling Tai,
Yadong Jiang,
Guangzhong Xie,
et al.
Show abstract
Polyaniline/titanium dioxide (PANI/TiO2) nanocomposite thin films were synthesized by in-situ self-assembly method,
which were doped with p-toluene sulphonic acid (p-TSA) and hydrochloric acid (HCl), respectively. The thin films were
characterized by using UV-Vis absorption spectroscopy and scanning electron microscope (SEM), and the NH3 gas
sensitive properties of the thin films were investigated at room temperature. The results showed that the PANI/TiO2 thin
film doped with HCl was superior to that doped with p-TSA in terms of response-recovery characteristics. The surface
morphology characterization of the thin films were performed to explain the different gas-sensing properties.
Fabrication and NO2 sensing properties of ChemFET sensors with self-assembly PAN/PSSA sensitive films based on nano-Au surface
Yadong Jiang,
Huiling Tai,
Guangzhong Xie,
et al.
Show abstract
Au colloids were synthesized using NaBH4 or Na3-sitrate with ethanol as solvent and nano-Au thin films were built up
by the electrostatic self-assembly technique. The self-assembled polyaniline (PAN) and poly (styrenesulfonic acid)
(PSSA) composite films (PAN/PSSA) were obtained by doping-induced deposition effect above the nano-Au film
surface. A novel chemical field-effect transistor (ChemFET) gas sensor was designed and fabricated with PAN/PSSA
composite films deposited on the gate area of MOSFET replacing the gate metal, and the gas-sensing properties of the
ChemFET sensor to NO2 was examined. The effects of the back-surface voltage and the channel length/width of
ChemFET sensor on the gas-sensing characteristics were investigated. The results showed that Au colloids synthesized
using ethanol as solvent was a monodisperse suspension and had more uniform distribution, and the PAN/PSSA
composite film on the nano-Au film surface was uniform and firm. The optimum response of the ChemFET sensor could
be obtained when the channel length and the ratio of channel width to channel length were 10μm and 10, respectively.
High performance NH3 gas sensor based on ordered conducting polymer ultrathin film
Show abstract
Conducting polymer ultrathin film shows promising future for gas sensor application due to their high conductivity and
excellent doping/dedoping performance. In this work, based on an modified Langmuir-Blodgett film method, ultrathin
conducting poly(3,4-ethylene dioxythiophene) (PEDOT) film was fabricated. The PEDOT ultathin film was
characterized by UV-Vis absorption spectrum, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy
(AFM) techniques. The results showed small PEDOT grains distributed in polymer LB films after the polymerization of
monomer. This ultrathin film exhibited an electrical conductivity about 1.2 Scm-1, and the conductivity increased and
decreased to 16.8 and 0.03 Scm-1 after doping and dedoping treatment. The interaction or response of films coated QCM
to NH3 have been tested and it has been found that sensitivity of the composite films on QCM showed better sensitivity
than bulk material. To the same analyte concentration, it increased with the increasing number of LB layers coated onto
QCMS before 80 layers, and then a decrease of sensitivity of QCM was observed after the layer number exceeded 80
layers. The interaction mechanisms between the ultrathin film and analyte vapor were also included.
Free modulation of defect states in multilayer structures consisting of epsilon-negative material and mu-negative material
Show abstract
By means of introducing defect layers into multilayer structures composed by epsilon-negative material and mu-negative
material, the free modulation of single and double localized modes in zero-φeff gap is realized respectively through
adjusting the thickness of different kinds of defect layers in two designed structures. In addition, the defect modes in the
zero-φeff gap, being distinct from those in the Bragg gap, have the property of insensitivity to incident angle and
polarization in some degree, which would be applied widely in tunable omnidirectional filters.
High diffraction efficiency for multi-layer dielectric gratings with rectangular groove
Show abstract
The purpose of this study is dedicated to the new design of the Multi-layer dielectric grating with the best performance
giving a highly diffraction efficiency in the -1 order, by using the rigorous coupled wave Analysis (RCWA). The
formulation for the implementation of the RCWA for multi-layer dielectric gratings incorporating the developed
enhanced transmittance approach is presented. An optimized design of multi-layer dielectric grating working at 1053-nm with TE polarized light and 51.2° incident can obtain the diffraction efficiency of 99%.
Rigorous coupled-wave analysis for the optical character of multi-layer dielectric thin film
Show abstract
The optical property of multi-layer dielectric thin film is determined by its operation on the more or less complete
cancellation of the light reflected at the upper and lower of the multi-layer interface of the thin film. An enhanced,
numerically stable transmittance matrix approach based on rigorous coupled-wave analysis (RCWA) is applied to the
analysis of optical character for multi-layer dielectric thin film. A design of a thin film stack used in multi-lay dielectric
grating was presented by using the method of RCWA. The numerical calculation shows that RCWA is a relatively
straightforward and deterministic technique for analysis the optical property of multi-layer dielectric thin film.
The optimization of zero-order diffractive filters for security imaging applications
Show abstract
As a result of the coupling process between the incident and the guided waves, the zero-order reflection exhibits a
narrow spectral response. There were some investigations on how to control the reflectance response of filters which
have diffractive structures. But these investigations only considered the case at the 0 deg azimuthal angle. In this work,
one optimized structure of ZODF which had conspicuous spectral shift effect and certain spectral response for the TE
polarization mode was given.