Proceedings Volume 9068

Eighth International Conference on Thin Film Physics and Applications

Junhao Chu, Chunrui Wang
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Proceedings Volume 9068

Eighth International Conference on Thin Film Physics and Applications

Junhao Chu, Chunrui Wang
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Volume Details

Date Published: 13 December 2013
Contents: 3 Sessions, 65 Papers, 0 Presentations
Conference: Eighth International Conference on Thin Film Physics and Applications (TFPA13) 2013
Volume Number: 9068

Table of Contents

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Table of Contents

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  • Front Matter: Volume 9068
  • Physics of Thin Film & Thin Film Materials
  • Technology of Thin Film & Application of Thin Film
Front Matter: Volume 9068
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Front Matter: Volume 9068
This PDF file contains the front matter associated with SPIE Proceedings Volume 9068, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.
Physics of Thin Film & Thin Film Materials
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Controllable fabrication and modulations on oxide nanotube arrays toward high performance solar cells
Hong Liu, Liang Tao, Yan Xiong, et al.
TiO2 nanotubes have been now an attractive nanostructured material due to their unique opto-electronic catalytic ability, compatibility to particle materials and feasibility to fabricate. However, these advantages were usually limited by morphological and structural defects from the electrochemical anodization method. More detailed understandings of the tube formation process are also needed. We have systematically investigated the tube formation with varying conditions. Beside discovery of new nanosphere structure, we have systematically investigated the spontaneous oscillating phenomena in potentiostatic anodization of TiO2 tubes. Consequently, we have established a novel comprehensive physical and chemical method that effectively influences the morphology and structural properties of TiO2 nanotubes. With assistance of periodical anodic voltage and moderate mechanical stirring, the efficiency of dye sensitized solar cells (DSSCs) can be significantly enhanced. For instance, the efficiency of DSSC with small TiO2 islands in the anode can be 114% higher than the control sample. This method has also turned the efficiency of DSSC with TiO2 nanotubes by low temperature current annealing into announceable value (from 2.05% to 3.51%).
Dependence of annealing temperature on microstructure and photoelectrical properties of vanadium oxide thin films prepared by DC reactive sputtering
Yan Li, Dongping Zhang, Bo Wang, et al.
Vanadium oxide thin films were prepared by DC reactive sputtering method, and the samples were annealed in Ar atmosphere under different temperature for 2 hours. The microstructure, optical and electrical properties of the as-grown and treated samples were characterized by XRD, spectrophotometer, and four-probe technique, respectively. XRD results investigated that the main content of the annealed sample are VO2 and V2O5. With annealing temperature increasing, the intensity of the VO2 phase diffraction peak strengthened. The electrical properties reveal that the annealed samples exhibit semiconductor-to-metal transition characteristic at about 40°C. Comparison of transmission spectra of the samples at room temperature and 100°C, a drastic drop in IR region is found.
Growth and physical properties of Ba1-xLaxSnO3 films grown on SrTiO3 substrates by sol-gel method
Chao Shan, Ting Huang, Zhigao Hu, et al.
Perovskite-structured Ba1-xLaxSnO3 (x=0.04, 0.06, 0.08) (BLSO) films were epitaxially grown on SrTiO3 (001) substrates by a sol-gel method. The microstructure and surface of the films were analyzed by X-ray diffraction and atomic force microscopy, respectively. The results show that the films exhibit preferred orientation along the c-axis without cracks or voids. Optical properties were studied in a wide photon energy range between 1.1 and 5.9 eV by spectroscopic ellipsometry. It was found that the optical band gap of the BLSO films increases gradually from 3.42 to 3.73 eV with increasing La concentration.
Point defects in the silicon nanowire
The single vacancy, the interstitial atom and the substitution atom are the point defects existing in the semiconductors mainly. The geometry and the effect of point defects on the electronic property of the silicon nanowire (SiNW) were theoretically studied in this work. The energy calculation showed that the substitution-vacancy pair was an energetically favored defect formed in SiNWs. Moreover, from the electronic band structures it was found that, the coupling between a substitution atom and a vacancy takes place at a long distance. The formation of a substitution-vacancy pair results in an energy shift of the bands and the vanishment of the donor level of the doped SiNW. So, the existence of a single vacancy takes great effect on the manufacture of the doped SiNWs.
Preparation of CuInSe2 thin films by spin-coating and selenization
Niangjuan Yao, Jianhua Ma, Xiaojing Zhu, et al.
In order to fabricate low cost and printable CuInSe2 (CIS) thin film solar cells, a chemical process has been developed to fabricate uniform CIS films with large grain size and close stoichiometry to chalcopyrite phase. Cu(NO3)2, InCl3 and ethyl cellulose (EC) were adopted to form the starting solution. CIS films were prepared by spin-coating and selenization. Precursor films and CIS films were investigated by SEM, EDS and XRD. CuCl and InCl3 crystals appeared in the precursor films. During the selenization process, CuCl first reacted with Se vapor to form Cu2-xSe. With increasing selenization temperature, InCl3 reacted with Cu2-xSe to form CIS accompanying the evaporation of chlorine in the form of gas. It is revealed that the element ratio in final CIS film is determined by the raw material ratio in the starting solution and the selenization temperature.
Growth of ZnSe-based longitudinal twinning nanowires by phase transformation
Jing Xu, Aijiang Lu, Chunrui Wang, et al.
Zinc blende ZnSe longitudinal twinning nanowires (Type I) and a sandwich structure with the wurtzite ZnSe inserting into the zinc blende ZnSe longitudinal twinning nanowires (Type II) are fabricated via a simple thermal evaporation method. The growth of them might be caused by the crystal plane slip during the phase transformation process from wurtzite ZnSe to zinc blende ZnSe nanowire. The wurtzite ZnSe might have two origins: 1) The phase transformed wurtzite from zinc blende. At first, during the temperature rising stage in the experiment, before the temperature approached to the transformation temperature (Ttr), ZnSe in zinc blende phase might begin to nucleate and grow. Once the temperature is higher than Ttr, the zinc blende products would transform to wurtzite phase. 2) The new-born nuclei grown wurtzite phase at high temperature for it is reported that the wurtzite phase is more stable at higher temperature. During the cooling period, the source material is exhausted and no more nucleation would occur. Some of the wurtzite products would transform to zinc blende phase when the temperature is lower than Ttr. During the process, it is reasonable that the ZB phase begins to form from the outer sides of an individual nanowire. Once the process completes, the longitudinal twinning ZB nanowire would be obtained; otherwise, the sandwich-structured nanowire forms.
Atmospheric pressure glow discharge deposition of thermo-sensitive poly (N-isopropylacrylamide)
Ming Shao, X. L. Tang, D. Wen, et al.
In this paper, a self-made atmospheric pressure dielectric barrier discharge reactor on intermediate frequency is brought forward and developed, which is equipped with power supply of 1-20 KHz, and the working gas is argon. The experimental results show that is a very stable and uniform atmospheric pressure glow discharge (APGD). Through a series of experiments, the waveforms of single pulse and multi-pulse glow discharge were both obtained. The voltage amplitude, discharge gap and dielectric material are studied, and the conditions of multi-pulse glow discharge are discussed as well. The novel methods of depositing poly (N-isopropylacrylamide) (PNIPAAm) coatings on the surface of glass slides and PS petri dish are provided by atmospheric pressure plasma polymerization. PNIPAAm can be obtained by plasma polymerization of N-isopropylacrylamide using the self-made equipment of atmospheric pressure plasma vapor treatment. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. SEM analysis has revealed that the PNIPAAm coatings were formed on the surface of the smooth glass slides. Further evaluation by using XPS, it has shown the presence of PNIPAAm. The wettability can be significantly modified by changing of the temperatures at above and below of the lower critical solution temperature (LCST) from the data of the contact angle test. These results have advantage for further application on the thermo-sensitive textile materials.
Structural, optical and electrical properties of delafossite CuGaO2 films grown by sol-gel method
M. J. Han, T. Huang, J. Z. Zhang, et al.
Transparent p-type conductive CuGaO2 films have been fabricated on sapphire substrates by sol–gel method. The stable sol solution for CuGaO2 were formed by copper(II) acetate monohydrate and gallium(III) nitrate hydrate, and the c-axis orientation of CuGaO2 films were strengthened with increasing annealing temperature. The pure phase CuGaO2 film was obtained at 900°C for 30 min in N2 atmosphere, and its microstructure, compositions, optical and electrical properties were analyzed. It was found that the sol-gel derived CuGaO2 films show a high optical transparency (60-80%) in the visible region, the direct and indirect band gaps were approximately 3.56 and 3.24 eV, respectively. It shows a crossover from the thermal activation behavior to that of three-dimensional variable range hopping from the temperature-dependent electrical conductivity at about 160 K.
Synthesis and optical properties of the (La, Mn)-codoped BiFeO3 films on n+-Si(100) substrates
J. Z. Zhang, T. Huang, Y. W. Li, et al.
La-doped BiFe0.92Mn0.08O3 films with the composition from 0 to 20% (BLFMx) have been deposited on Si(100) substrates by a sol-gel route. X-ray diffraction analysis shows that the films are polycrystalline and exhibit the pure perovskite phase structure (R3c). The La dopant effects on the surface morphology, dielectric function, and optical transition of the films have been investigated by atomic force microscopy and spectroscopic ellipsometry at room temperature. The dielectric functions of the films have been uniquely extracted by fitting the measured ellipsometric spectra with a three phase layered model (air/film/Si) and the Tauc-Lorentz dielectric function model in the photon energy range of 0.5-3.5 eV. It is found that the optical transitions decrease with increasing La composition, which is crucial for future photoelectric device.
Structural and stable properties of ZnSe/Si core-shell nanowire heterostructures: The first principles calculation
Yijie Zeng, Bofan Zhou, Yan Huang, et al.
Relations between composition and structural and stable properties of cubic zinc selenide-silicon core-shell nanowires (NWs) are studied by first principles calculation. The diameter is between 1.1 and 2.7 nm, and the direction of the NWs considered is [110]. The lattice constants of the nanowires deviate from the Vegard’s law positively with compressed ZnSe core. Stability of the NWs is discussed by taking binding energy into account. Pure Si NWs show an increasing trend of binding energy as the diameter increases while ZnSe NWs do not. Further analysis shows that zinc blende ZnSe NWs might be unstable under small diameters and a phase transition to wurtzite structure would occur. Our findings might give some guidance for the application of ZnSe/Si core-shell NWs in photoelectronics.
Model for atomic layer deposition on inner wall of rectangular pipes with large aspect ratio
Yuqing Xiong, Maojin Dong, Kun Li, et al.
Feasibility of thin films deposited on inner wall of rectangular pipes with length aspect ratio up to 50 by atomic layer deposition was studied, by solving kinetics equation of gas adsorption on inner wall of pipes. And the time for reactants to reach saturated adsorption in pipes was calculated. Furthermore, the process of thin film deposition by atomic layer deposition was simulated by Kinetic Monte Carlo method, and a growth model for atomic layer deposition of aluminum on inner wall of long rectangular pipes was established.
Carrier sign reversal in amorphous silicon ruthenium thin films deposited by co-sputtering
Anran Guo, Jian He, Chong Wang, et al.
We report on the co-sputtering growth of amorphous silicon ruthenium (a-Si1-xRux) thin films, in which carrier sign reversal is observed by Hall measurement with increasing Ru concentration. High conductivity and suitable temperature coefficient of resistivity (TCR) are obtained, respectively. Raman spectroscopy reveals the degradation of amorphous network, which is caused by doped Ru atoms due to the different size and eletronegativity between Si and Ru atoms. The Hall effect anomaly will be related to the impurities and disordered structure.
Magnetic and electronic structural properties of the GdGa7N8 cluster
Yanbian Fang, Bofan Zhou, Yan Huang, et al.
Geometric optimizations and calculations of GdGa7N8 cluster were performed by a DMoL program using spin-polarized density functional theory (DFT). The binding energy, HOMO-LUMO gap, Mulliken charge and bonding characteristics were computed and analyzed. It is found that the Gadolinium substituting the Gallium would make the bonds between itself and neighboring atoms longer than that of the undoped cluster. The magnetic moment of GdGa7N8 was found to be 7 μB. And most of the magnetic moment was focused on the Gd atom owing to its half-filled 4f-shell.
Effects of post annealing on structural, electrical and optical properties of ZnO:Al thin films prepared by RF magnetron sputtering
Jianhua Ma, Yan Liang, Niangjuan Yao, et al.
Al doped ZnO (ZnO:Al, AZO) thin films were deposited on ordinary soda-lime glass (SLG) substrates by RF magnetron sputtering. Effects of post annealing (300~600 °C for 2~30 min in air and N2, respectively) were studied. All the films were wurtzite structure with highly c-axis preferential orientation. Their electrical properties were relatively stable at the post annealing temperature of 300 °C. As the temperature further increasing, post annealing in air leaded to drastic degradation in the electrical properties, while that in N2 had relatively small influence. Diffusion of alkali ions from SLG substrates was deduced to be one of the influence factors for electrical properties. The spectra measurements showed that the post annealing mainly affected the transmittance in the near-infrared and infrared (NIR-IR) range and the optical band gap (Eg). The variation of Eg was attributed to the Burstein-Moss (BM) shift modulated by many-body effects.
Vanadium dioxide thin films for smart windows: optical design and performance improvement
Xinfeng He, Congcong Gu, Fei Chen, et al.
The high quality vanadium dioxide (VO2) thin films have been fabricated successfully on sapphire by a simple novel sputtering oxidation coupling (SOC) method. Transmittance spectra of vanadium dioxide film have been measured between 25 °C and 90 °C. The thin film samples exhibit a good insulator-metal transition near room temperature. The optical constants of VO2 thin film samples were derived by fitting the transmittance spectra using the Drude-Lorentz model. In order to improve the transition efficiency, the thin film thickness was optimized by the optical design. The calculated results with different thin film thickness show that VO2 thin film with 84 nm owns a maximums value of the transition efficiency. This research will promote VO2 thin film optical performance improvement for the smart windows.
The study of substrate material for deposited titanium nitride thin film and its influence
Shuying Fu
In the paper, the TiNx thin film was prepared with two substrate Si-p(111) and Si-p(100) by dc reactive magnetron sputtering method and their performance was studied. The results show that the XRD diffraction peak with Small number, peak shape Octavia is not overlapping with TiNx diffraction peak for TiNx thin film with p-si(111) substrate. But, the film is of preferred orientation for (200). And all these were responsible for analysis of TiNx thin film growth on its structure and crystalline. Therefore, the deposition of TiNx thin film is appropriate for p-si(111) substrate. It can meet the requirements of the preparation of optical thin film quality.
Influence of laser irradiating energy on optical properties and morphology of TiO2 films
Fang Guo, Junqi Xu, Junhong Su, et al.
The optical thin film parts are important components used in the laser systems. In practice, the electromagnetic field generated by the laser will make complex and diverse changes on the films, but the fundamental related with properties changing is not clear. For the purpose of recognizing the variation of TiO2 films irradiated by the laser, TiO2 films were prepared on K9 substrates at the same experimental conditions with the exception that the irradiating laser energy was different to investigate effects about the film’s properties and morphology between the before and after irradiation. The following film’s factors: transmittance, refractive index, extinction coefficient, film thickness and laser-induced damage threshold (LIDT) are included in experimental results, also, morphology and roughness by an Atomic Force Microscope (AFM) and a Taylor Surf CCI 2000 non-contact instrument are needed. The result showed that irradiating laser can decrease TiO2 films’ transmittance and roughness, and increases the films’ refractive index and LIDT. Furthermore, the results indicated that different laser energy cause the different morphology of films.
Optical and electrical properties of Mn1.56Co0.96Ni0.48O4 thin films
Y. Q. Gao, Z. M. Huang, Y. Hou, et al.
Mn1.56Co0.96Ni0.48O4 (MCN) films with different layers have been prepared on Al2O3 substrate by chemical solution deposition method. The microstructures, optical and electrical properties of the films are investigated. X-ray diffraction and microstructure analyses show good crystallization and both the crystalline quality and the grain size are improved with the increasing thickness of the films. Mid-infrared optical properties of MCN films have been investigated using transmission spectra. The results show the red shift of absorption with the increasing film thickness and the energy gap Eg decrease from 0.6422 eV to 0.6354 eV. All the MCN films show an exponential decrease in the resistivity with increasing temperature within the measured range. The temperature dependence resistivity can be described by the small polarons hopping model. Using this model, the characteristic temperature T0 and activation energy E of the MCN films were derived. With the film thickness increase, the T0 and E of the MCN films increase. The calculated room temperature coefficient of resistance (TCR) of MCN film with 100 layers is -3.5% K-1. The MCN films showed appropriate resistance and high value of TCR, these advantages make them very preponderant for thermal sensors.
Design of chirped mirrors used for the dispersion compensation in femtosecond lasers
Chunyan Liao, Junjun Qin, Manli Hu
Negative dispersion dielectric multilayer mirrors have contributed significantly to the enhancement of the performance, compactness and reliability of femtosecond lasers. There are two alternative approaches that are widely investigated for dispersion compensation: chirped mirrors and Gires-Tournois mirrors. Chirped mirrors can exhibit a broad smooth high reflectance range if the layer thickness is superimposed a quasi-periodic modulation on a linear variation of the optical thickness of the layers. The performance of such chirped mirrors is calculated and the factors affecting the performance are discussed in detail. In such chirped mirrors, the performance is strongly affected by the expected bandwidth and modulation period of the optical thickness of the layers.
Effects of substrate temperature on morphology, structure and chemical composition of Cu2S films
Cu2S thin films have been deposited on CdS/ITO (In2O3:Sn) substrates with various substrate temperatures by DC magnetron sputtering method. The effects of substrate temperature on the crystallization behavior and morphology are studied. Chemical composition of the films is confirmed by energy dispersive X-ray (EDX) spectroscopy. X-ray diffraction (XRD) analysis of the films reveals they have polycrystalline chalcocite structure with (110) texture. Field emission scanning electron microscopy (FESEM) show the crystalline nature of the films at higher substrate temperature, which is in accordance with XRD measurements. Stoichiometric analysis exhibits element composition with Cu/S concentrations ratio equal to 2 approximately.
Thin film poly-crystalline silicon fabrication based on Rapid Thermal Annealing (RTA) process
Rapid Thermal Annealing (RTA) process was introduced to the experiment of Aluminum-induced crystallization of a-Si, based on sputtering method, on low cost glass substrate. A stack of glass/Al (150 nm)/Si (220 nm) was deposited by sputtering sequentially. Samples were annealed under RTA process, then annealed in the tube annealing furnace at 400 °C for 5 h. The grain crystallization was inspected by optical microscopy (OM), ,Raman spectroscopy, X-ray diffraction (XRD),and energy dispersive spectroscopy (EDS). The preferential orientation (111) was observed, with a Raman Peak at 520.8cm-1, Different annealing periods were discussed.
Electrical properties of polycrystalline mercuric iodide detector
Yang Liao, Dongmei Li, Jirong Li, et al.
Potentially low cost and large area polycrystalline mercuric iodide is one of the preferred materials for the fabrication of room temperature X-ray and gamma-ray detectors. The properties of the contact between electrode and film play an important role in the performance of the polycrystalline mercuric iodide detector. The crystalline structure of the as-deposited polycrystalline α-HgI2 films were characterized by XRD. The surface morphology of the films was obtained by optical microscope and scan electron microscopes (SEM). And the I-V curve and the response to 241Am were measured after evaporating Au electrode. The energy resolution of 241Am α particles at room temperature was obtained.
Preparation of graphite and graphene thick film on AlN substrate
Saijie Gao, Yue Shen, Feng Gu, et al.
High-purity AlN ceramic substrate was prepared by conventional sintering in N2 atmosphere at 1710°C for 3 hours. Measurement results of SEM, X-ray Diffraction (XRD) indicated that the AlN substrate was sintered completely, average particle size is about 1-3 μm and the porosity is very low. Graphite and graphene electrodes were obtained by simple doctor-blade coating method on AlN substrate. The samples were investigated by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope (SEM). Sheet resistance is measured by the four-probe method. Annealing at H2 reduction atmosphere can slow down graphitized trend of graphene and protect it’s structure. The graphite electrode was applied in typical sandwich-structure DSSCs with ZnO as photoanodes, and the photoelectric conversion efficiency (η) was about 0.78%, which can be optimized and applied in DSSCs by process optimization.
Preparation of graphene/polymer composite photocathode for QDSSC
Qiandi Wang, Yue Shen, Jie Tan, et al.
Graphene (rGO) was fabricated by modified Hummers method and a reducing process. Conductive polymer/graphene films were obtained by scalpel technology and used as photocathode in CdS quantum dot-sensitized solar cell (QDSSC). Polymers used in this paper were ethyl cellulose (EC), polyphenyl vinyl (PPV) and polyvinyl butyral (PVB), respectively. The obtained composite films were investigated by X-ray diffraction, Raman spectroscopy technology and scanning electron microscope (SEM). The photoelectric properties of QDSSCs were tested under AM 1.5 irradiation. Test results show that the film performance of the EC/rGO and PPV/rGO photocathode have been improved effectively. Power conversion efficiency (PCE) of the relative QDSSCs under AM 1.5 irradiation were 0.81% and 0.86%, respectively.
Energy transfer from CdSe quantum dots to graphene
Chunyan Liao, Xiuhong Zhu
Graphene-CdSe quantum dots hybrid is a promising structure to combine unique properties of graphene and quantum dots. In this work, graphene was firstly prepared on a 300 nm SiO2/Si substrate by mechanical exfoliation of a highly oriented pyrolytic graphite using scotch tape. Then the samples were immersed in CdSe quantum dots solutions for 15 minutes and followed by water flush. The graphene-CdSe quantum dots hybrid structures were obtained due to the electrostatic adsorption of CdSe quantum dots on graphene. Fluorescence quenching of CdSe quantum dots on graphene was found, which probably indicates the energy transfer from CdSe quantum dots to graphene. The results suggest that graphene is a good candidate for manipulating energy transfer of quantum dots due to its extremely high carrier mobility.
Microstructure and electrical properties Of PMNT thin films prepared by a modified sol-gel process
Aiyun Liu, Hailong Han, Linlin Wei, et al.
0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMNT) thin films were prepared on (111)Pt/Ti/SiO2/Si substrate by a modified sol-gel process with Nb2O5 as the niobium source. XRD analysis shows that PMNT thin films with pure perovskite were obtained by spin-coating and annealing at 700°C for 20 minutes. The remanent polarization and coercive field of the PMNT thin films are about 7.69μC/cm2 and 80.75kV/cm, respectively. The dielectric and C-V curve of PMNT thin films are also investigated. The dielectric constant ( εr ) reaches 935 and the dissipation factor (tanδ)is about 0.04 at 1kHz.
Effects of thermal treatment on Cd1-xZnxTe thin films deposited by close-spaced sublimation
CdZnTe thin films were deposited on FTO (SnO2: F)-coated glass substrates by close-spaced sublimation method and then annealed under three different conditions. The influences of the three thermal treatments on the structure, morphology, composition and optical properties of the CdZnTe thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectra (EDS) and photoluminescence (PL) spectroscopy. The XRD results show that the films are (111) preferred orientation. The SEM and PL spectroscopy results show the better crystalline quality after any of three thermal treatments than that of as-deposited sample. The EDS analysis indicates that the Zn composition decreases for the sample with CdCl2 annealing, but increases for the sample annealing directly and ZnCl2 annealing. The same results are also obtained by XRD and PL spectroscopy.
The evolution of polymer surface topography in annealing
Pengfei Ma, Weiguo Liu, Huan Liu
Ultrasmooth polymer films are of great importance in a large body of technical application. Photoresist technology plays a very important role in MEMS, and usually is to use optical coatings to transfer the smooth surface. In order to form different value of roughness is bright and clean surface or sacrifice layer microstructure, surface topography and its effect on the microstructure is crucial. Photoresist thin film EPG533 having different thicknesses of 270nm, 500nm, and 1 μm were deposited onto well-cleaned n-type silicon substrates by spin coating and annealed in the range from 100°C to 200°C.The effects of thermal annealing and thickness variation on the crystalline quality and surface morphology of the films were investigated by white light interferometry measurements. It was found that the film quality and morphology depend on the annealing temperature. The root-mean-square roughness and waviness on the surface change, as a result of increasing film thickness.
Highly (222)-oriented pyrochlore PZN-PT thin films prepared by pulsed laser deposition
H. L. Han, A. Y. Liu, L. L. Wei, et al.
Highly (222)-oriented 90%Pb(Zn1/3Nb2/3)O3-10%PbTiO3(abbreviated PZN–PT) thin films, about 550nm in thickness, have been successfully grown on (111)Pt/Ti/SiO2/Si substrate by pulsed laser deposition method. Pure pyrochlore phase with highly (222)-preferred orientation, determined by X-ray diffraction, was formed in the PZN–PT thin films when the temperature of substrates is 550°C. FE-SEM investigation shows that the surface appearance and the cross section of the films are smooth and crack-free with some dispersive spherical protrusions. The dielectric constant and loss of the thin films were measured using an impedance analyzer (HP4194A). The dielectric constant ( εr ) and the dissipation factor ( tanδ ) at 1 kHz are 205 and 0.03, respectively.
Study on the fabrication and releasing of sacrificial layer of micro-cantilever
Liang Liu, Weiguo Liu, Huan Liu
Polyimide is used as sacrificial layer material during the research on bi-material micro-cantilever structure. Contrasted with other sacrificial layer materials, polyimide is marked with excellent properties, like good insulation, big coefficient of elasticity, big coefficient of linear expansion and outstanding mechanical property. This dissertation has studied the preparing process of sacrificial layer, like sacrificial layer imaging and solidifying, and different methods to release sacrificial layer and how to control all kinds of parameters to obtain the best suspension. Finally, the optimized process parameters are obtained.
Large strain response in PZT-PZN-PAN lead-based ceramics
Linlin Wei, Aiyun Liu, Hailong Han, et al.
Solid solutions of 0.8Pb(Zr0.52Ti0.48)O3-(0.2-x)Pb(Zn1/3Nb2/3)O3-xPb(Al1/2Nb1/2)O3 (PZT-PZN-PAN, PZT-PZN-xPAN) with x from 0 to 0.1 were fabricated and the dielectric, ferroelectric, piezoelectric properties were investigated in detail. Results show the crystal structure changes from coexists of tetragonal and rhombohedral to single rhombohedral phase. At a critical composition of 0.02, a maximum quasi-static piezoelectric coefficient d33 (410 pC/N) was obtained. Furthermore, it is found that the increment of PAN content could lead to increase the strain of PZT-PZN-xPAN ceramics, and a large strain response of ~0.24% with normalized strain Smax/Emax as high as 767 pm/V was obtained for the PZT-PZN-0.1PAN under a low electric field of ~3 kV/mm, which makes it a promising material for solid-state actuator applications.
Structural characterization of multilayer using the analysis combining GIXRF with GIXRR method
Xiaoyue Yang, Wenbin Li, Jingtao Zhu, et al.
Grazing incidence X-ray reflectivity (GIXRR) and X-ray fluorescence (GIXRF) are complementary techniques for the characterization of layered materials. It is shown that the analysis of multilayers by this combined technique can overcome the deficiencies of individual techniques. In this study, Si(sub)/W/Ni/Ti/Ni was studied using grazing incidence X-ray reflectivity and X-ray fluorescence. It is suggested that the geometrical factor correction in GIXRF analysis can be avoided by using the intensity ratio of the fluorescence yields from Ni-Kα and Ti-Kα. Additionally, the fluorescence intensity of Ni-Kα, Ti-Kα, Si-Kα and the elastic scattering are analyzed quantitatively with the corresponding GIXRR profile to obtain reliable structural parameters about the sample.
Effect of surface morphology on laser-induced crystallization of amorphous silicon thin films
Lu Huang, Jing Jin, Guohua Wang, et al.
The effect of surface morphology on laser-induced crystallization of hydrogenated intrinsic amorphous silicon (a-Si:H) thin films deposited by PECVD is studied in this paper. The thin films are irritated by a frequency-doubled (λ=532 nm) Nd:YAG pulsed nanosecond laser. An effective melting model is built to identify the variation of melting regime influenced by laser crystallization. Based on the experimental results, the established correlation between the grain growth characterized by AFM and the crystalline fraction (Xc) obtained from Raman spectroscopy suggests that the crystallized process form amorphous phase to polycrystalline phase. Therefore, the highest crystalline fraction (Xc) is obtained by a optimized laser energy density.
An investigation of passivation properties of SiNx-Si interface by an MIS model
Jun Wang, Meijie Han, Xueliang Ma, et al.
This paper presents a new way to study passivation mechanism of SiNx-Si interface using capacitance-voltage method. Fixed charge density (Nf) near dielectric/Si interface, which is closely related to field effect passivation, and interface trap density (Dit) at dielectric/Si interface, which is closely related to chemical passivation, can be obtained directly from experimental CV characteristics. The passivation properties of SiNx-Si can be studied and optimized by the MIS model.
TiO2 nanocrystals coated rutile nanorod microspheres as the scattering layers for dye-sensitized solar cells
Mengyu Gao, Hongzhi Wang, Yaogang Li, et al.
Anatase TiO2 nanocrystals were deposited on the rutile TiO2 nanorod microspheres (NCRNMs) via the controlled hydrolysis and condensation of titanium (IV) bis(ammonium lactato) dihydroxide (TALH) in the presence of polyethyleneimine (PEI). The anatase TiO2 nanocrystals prevented the growth of rutile TiO2 nanorod microspheres from sintering process. By coating of anatase nanocrystals, the decreasing of specific surface area of rutile TiO2 nanorod microspheres (RNMs) were efficiently inhibited. The specific surface area of NCRNM was 47.0 m2/g after sintering at 500 °C,which was 50% increment compared to RNM. The dye sensitized solar cells (DSSCs) were assembled using the semitransparent underlayers and NCRNM scattering layers as the photoanodes. The incident photon to current conversion efficiency (IPCE) analysis showed the DSSCs in the presence of NCRNMs adsorbed more dye molecules while kept a high light-harvesting efficiency. The cell covered with the NCRNM scattering layer had the efficiency of 7.33%, which was 20% increment compared to that of the absence one.
The photoluminescence and thermoluminescence properties of nanoporous alumina films which processed in different annealing conditions
Ning Xie, Kai-di Ma, Qian Wang
The single-crystal α-Al2O3: C is a highly sensitivity dosimeter to ionizing radiation. However, the crystal grows requires high temperature and reducing atmospheres. Nanoporous anodic alumina is easy to fabricate, low cost, do not need these conditions of specialties and has been demonstrated a highly sensitive thermoluminescent dosimeter for ionizing radiation. In this paper, we get the nanoporous alumina films by two-step anodic oxidation. We present the photoluminescence (PL) and thermoluminescence (TL) properties of alumina films, which annealed under different temperature and atmosphere. From the photoluminescence emission spectra of nanoporous alumina films, we found that PL peak appears in the 450nm, the intensity of the PL peak increases with elevated annealing temperature and reaches a maximum value at 500°Cwhen the temperature is under 600°C. TL measurements show that the nanoporous alumina films after an annealing treatment present the strong and broad TL glow peaks at ~200°C. The TL intensity increase with the increase of annealing temperature. The nanoporous alumina films annealed in the air at 600°C have a linear dose response in the dose range of 5–1000 Gy for 60Co gamma radiation and have the highest TL sensitivity. We compared these luminescence characteristics with crystal α-Al2O3: C, we found that the nanoporous alumina annealed in the different annealing conditions have the same characteristic in the luminescence. So we could try to take the place of it with a lower cost.
Vibrating property of single Ge based heterostructure nanowires
Yao Zhang, Chunrui Wang, Jing Xu
Raman spectrum of single heterostructure nanowire can reflect its unusual lattice vibrations as well as the junction features. In this paper, we report Raman spectra of two morphologies of single Ge based heterostructure nanowire, that is, one is CdSe/Ge biaxial heterostructure nanowires(sample I), another is Ge nanowires is surrounded by CdSe nanoparticles (sample II), which is fabricated by one step thermal evaporation of CdSe and Ge powder. A new mode was observed in Raman spectrum of Ge nanowires surrounded by CdSe nanoparticles, which caused by the interaction of LO mode of CdSe and LO (TO) mode of Ge. The LO (TO) mode of Ge nanowire in CdSe/Ge biaxial heterostructure nanowires and Ge nanowires surrounded by CdSe nanoparticles all has a red-shift in comparison with that of Ge nanowires. The vibrational mode of CdSe in CdSe/Ge biaxial heterostructure nanowires has a red-shift. The vibrational mode of CdSe in Ge nanowires surrounded by CdSe nanoparticles has a blue-shift. The red-shift mode may be caused by quantum confinement effect. The blue-shift mode may be originated from tensile stress or high density of stacking defects. The vibrating mode of the heterostructure nanowires was much sensitive to stacking fault than to quantum confinement effect when the diameter of nanowire is larger than 300nm.
Strains distribution in biaxial Ge/CdSe nanowire analyzed by a new finite element method based on boundary conditions
Dong Wang, Chunrui Wang, Yao Zhang, et al.
A new finite element method based on boundary conditions is proposed here to obtain the complete strains distribution in Ge/CdSe biaxial nanowires. The results show that the strains in nanowire is essentially uniform along the nanowire axis, whereas turn to be complex in cross-section. Additionally, Raman spectrum of Ge subnanowire was calculated on base of those strain data. Raman frequency shifts in Ge subnanowire in Ge/CdSe biaxial nanowires is a good agreement with that of Raman spectrum, which confirms the validity of this model.
Technology of Thin Film & Application of Thin Film
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Molybdenum (Mo) back contacts for CIGS solar cells
Xiaofeng Ma, Dingquan Liu, Lihong Yang, et al.
Mo metal back contacts for CIGS solar cells have been reviewed. The electrical resistivity, reflectance and adhesive properties of Mo thin films are affected strongly by the film deposition parameters. A Mo thin film with low resistivity and good adhesion can be obtained through two-step process. This bilayer Mo thin film can be formed through the different film structures depending on the working pressure. A MoSe2 layer formed at CIGS/Mo interface changes the CIGS/Mo hetero-contact from Schottky-type contact to ohmic-type contact. It also improves the adhesion between CIGS and Mo layers when its c-axis is parallel to the Mo surface. Additionally, it forms the back surface field for CIGS solar cells. However, the MoSe2 formation and c-axis orientation depend on the state of Mo prior to selenization, the medium of selenization, and the substrate temperature during selenization. At last, a single layer Mo thin film with low enough resistivity and good adhesion has been fabricated successfully by the pulse magnetron sputtering technology with appropriate deposition parameters.
Examination and simulation of effect of Ag2O content on heat mirror production
En-Shih Chen, Jin-Yu Wu, Chun-Wei Yang, et al.
We propose a method to determine the effect of Ag2O on heat mirror production processes. A heat mirror is a low emissivity ( low-E ) film with high visible transmittance, high infrared reflectance and vanishing infrared transmittance. We carried out a computer simulation to understand the effect of Ag2O on the spectrum of three-layered low-E films. We then prepared three-layered low-E samples with ITO buffer layers, which were deposited on the Ag layer at 0.6kW, 1kW, and 2kW sputtering power. The simulation showed that the peak visible transmittance decreased, the FWHM of the transmittance widened, and the infrared reflectance was lowered as the amount of Ag2O was increased. In experiments, the three-layered sample with the buffer sputtered at 0.6kW exhibited a lower peak transmittance, broadened FWHM, and decreased infrared reflectance, suggesting that higher levels of Ag2O were introduced. We also prepared five-layered low-E samples, which are of typical heat mirror structures, with buffer layers similar to the three layered samples. The transmittance and reflectance spectrum of the five-layered sample with the buffer sputtered at 0.6kW also suggested a higher Ag2O content than other samples. Therefore, studying the spectrum of the three-layered low-E film, along with the simulation, can be an economical way to optimize manufacturing processes in the production of five-layered low-E films.
Effects of temperature on internal friction of Graphit-iC graphite-like carbon coatings
Zhi-yong Zhu, Wen Shi, Zi Wan, et al.
Graphit-iC graphite-like carbon coatings were deposited on SDC90 cold work die steel by using an unbalanced magnetron sputtering technology. Effects of the temperature on microstructure and internal friction of the carbon coatings were characterized by Raman spectroscopy (Raman) and a low-frequency mechanical analyzer (LMA-1) testing system. The results indicate that the internal friction of the two-side deposited carbon coatings is small (2.17×10-4), being higher than one of the substrate (1.63×10-4), and increases with temperature. However, there is an internal friction peak at 250°C accompanied with partial sp3 transferred to sp2 and increasing the intensity ratio ID/IG. There is gradual graphitization tendency of the carbon coatings as temperatures increase from 25°C to 350 °C. This would be progressive transformation from amorphous to crystalline.
First-principles calculations of CsMX3(M = Sn, Pb; X = Cl, Br, I)
CsMX3(M = Sn, Pb; X = Cl, Br, I) are strong candidates for the fast high energy irradiation detectors, ionic conductors, and optoelectronic devices. There are many experimental and theoretical investigations devoted to the study of perovskites ABX3 (A is a cation with different valence, B is a transition metal and X is oxides, halides or chlorides). But there is no systematic study of CsMX3 using HSE approximation particularly. In this paper, the band structures, density of states and optical properties of CsMX3(M = Sn, Pb; X = Cl, Br, I) have been studied by first-principles calculations using both the hybrid functional (HSE) approximation and the PBE-GGA approximation. The results of both approximations are compared with the experimental values. The results of HSE are closer to the experimental values. The changes of properties have been founded by comparing the band structures, density of states and optical properties of this series of thin film materials respectively. The trend of impact on these properties by replace elements has also been found. Our results provide a basis for the design of specific performance thin film materials.
Control method for transition metal oxides as a hole-injection layer for organic light-emitting devices
Wejiang Zhang, Jie Zhang
The mechanism of transition metal oxide, molybdenum oxide (MoOx), used as interlayers in organic light-emitting devices (OLEDs) are investigated. The electronic structures and interfacial chemical reactions are investigated with ultraviolet and x-ray photoelectron spectroscopy. The influence of evaporation temperatures on the electronic structures of MoOx films and the electrical properties of organic light emitting diodes are investigated.
Fabrication of flexible conductive graphene thin films based on high water-soluble sulfonated-triazine non-covalent functionalized graphene
Yu Liu, Shanyi Guang, Xinyan Su, et al.
We report a facile and scalable fabrication of flexible conductive graphene thin films via a vacuum filtration method based on high water-soluble sulfonated-triazine non-covalent functionalized graphene colloid (STGNS). A novel sulfonated triazine (ST) molecule was synthesized using a one-step method to improve the dispersion stability of graphene during the chemical reduction. AFM image of STGNS sheets showed the STGNS is individual dispersion of graphene sheets in water. FTIR, and UV-vis revealed ST molecules were successfully loaded onto graphene sheets by hydrogen bonding anchoring and π–π stacking. It was found that the dark homogeneous suspension of the STGNS with concentration up to 4.5 mg mL-1 can remain stable with no visible precipitate for more than 6 months. The high watersoluble individually dispersed graphene colloid facilitated large-scale fabrication of flexible conductive graphene films with different thickness by adjusting the content of STGNS. The obtained graphene films exhibited a sheet resistance as low as ca. 5.6 KΩ-1 with 78% transparency at 550 nm.
Structure and magnetic properties of Ge99.04Mn0.96 thin film prepared by thermal evaporation of Mn doped GeO2 ceramic film under hydrogen atmosphere
Chengbin Jing, Hong Guo, Wei Bai, et al.
Ge99.04Mn0.96 thin film was fabricated by thermal evaporation of Mn doped GeO2 ceramic film under hydrogen atmosphere. Secondary phases were not detected by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analyses. The film is p type. Room-temperature ferromagnetism was detected in the film. The ferromagnetic behavior may arise from alignment of the bound magnetic polarons (BMP) mediated by the localized holes in the system as well as ultra small secondary phases unable to be detected by XRD and HRTEM analyses.
CVD diamond film oxidation resistance research
Longwei Jing, Xiaoping Wang, Lijun Wang, et al.
Diamond films were deposited on a silicon substrate by microwave plasma chemical vapor deposition system, and its oxidation experiments were carried out in atmospheric environmental condition by using a muffle furnace. Inatmospheric environment (the temperature is from 400°C to 900°C) the oxidation resistance of diamond thin films was investigated. The results indicate that under the atmospheric environment diamond thin film surface morphology did not change after 6 hours at 400°C. Diamond thin film surface morphology began to change after 2 hours at 600°C, and when time was extended to 4 hours, the diamond thin film surface morphology changed significantly. The surface morphology of diamond films began to change after 15 minutes at a 700°C condition and when time was extended to 6 hours diamond films were all destroyed. All the diamond films on the silicon substrate disappeared completely in 20 minutes at 900°C. The intact crystal face is the reason that natural diamond has stable chemical property. The crystal face of synthetic diamond film has a lot of defects, especially on the side. Oxidation of the diamond films begin with the grain boundary and defects.
Synthesis and field emission properties of graphene
Xiufang Pan, Lijun Wang, Xiaoping Wang, et al.
In this paper, a series of grahene films were fabricated on Ni coated Al2O3 ceramic substrates by using microwave plasma-assisted chemical vapor deposition (MPCVD) technique. Raman spectroscopy and scanning electron microscope (SEM) were used to study the microstructure and surface morphology of the film. The field emission (FE) property of graphene films was measured in a high vacuum system. Field electron emission results showed a turn on field is 3.5 V/μm, and current density is 90μA/cm2 at an electric field of 6 V/μm. The phenomenon of field emission was unstable and the current density was too small (no one exceeds 1mA/cm2). So the preparation method and process of graphene field emission device need further optimization, meanwhile, the mechanism and property of field emission require fully research.
Co-Sb thermoelectric thin films prepared by ion beam sputtering
Wei-fang Fan, Ping Fan, Zhuang-hao Zheng, et al.
Co-Sb is a new kind of promising thermoelectric material depending on its extremely high hole mobility, high thermoelectric power and relatively low thermal conductivity because of its complicated crystal structure. In order to obtain the best Co/Sb composition ratios, thin films with various Co/Sb composition ratios were obtained by ion beam sputtering technique with a fan-shaped target at room-temperature. The target was made by different Co and Sb plate’s areas. All the samples were annealed at 350 °C and 400 °C for one hour in vacuum chamber. The maximum Seebeck coefficient of the thin films was -210 μV/K when the thin film was annealed at 400 °C whose plate areas ratios of Co/Sb was 1:3. However the thin film possessing the maximum Seebeck coefficient has a large resistivity that causes the worse thermoelectric property. When plate ratio of Co/Sb is 1:4, the thin film had the maximum power factor of 1.56 mWm-1K-2 with an moderate seebeck coefficient of -41 μV/K and an conductivity of 9.3×105 Sm-1.
Growth and characterization of Sb2Te3 thin film deposited by pulsed laser method
Tantan Liu, Hongmei Deng, Pingxiong Yang, et al.
Sb2Te3 film was deposited on glass substrates which were heated at180°C by pulsed laser deposition (PLD) process using Sb2Te3 target. The crystal structure and crystallization behavior of Sb2Te3 film was determined by X-ray diffraction (XRD) and Raman spectra, respectively. The surface morphology of the film was measured by atomic force microscope (AFM). The results suggest that the crystalline of Sb2Te3 thin film was crystallized well when the substrate temperature (Tsub) was 180°C, which indicated that Sb2Te3 thin film can be fabricated by PLD at suitable temperature.
The influence of annealing condition on the properties of the Co-Sb thermoelectric thin films prepared by ion beam sputtering
Yin Zhang, Ping Fan, Zhuang-hao Zheng, et al.
Co-Sb based thermoelectric materials has been identified as a new promising thermoelectric material because of its extremely high hole mobility, high thermoelectric power, and relatively low thermal conductivity due to complexity in the crystal structure. In this work, Co-Sb based thin films were prepared by ion beam sputtering technique and the annealing process had been used to optimize the thermoelectric properties of the thin films. The results indicate that the thin films annealed at vacuum chamber with the chamber pressure of 6.0×10-4 Pa has worse thermoelectric properties than the thin films annealed at Ar atmosphere. The thin film with single CoSb3 phase which annealed at 400°C at Ar atmosphere has a maximum power factor of 1.8 mWm-1K-2 with the Seebeck coefficient of 50 μV/K and the conductivity of 7×105 Sm-1. Also, the thermoelectric voltage of the thin film is stable through the testing temperature increases.
Structural, morphological and infrared detection properties of Mn-Co-Ni-O spinel oxide films
Wei Zhou, Ouyang Cheng, Jing Wu, et al.
Mn-Co-Ni-O spinel oxide materials, with the prototype of AB2O4, are excelled in uncooled thermal sensing and infrared detection due to its high absolute NTC value and moderate resistivity at room temperature. In this work, Mn1.56Co0.96Ni0.48O4 film (MCN-CSD) and Mn1.40Co1.00Ni0.60O4 (MCN-RF) film are fabricated on amorphous sapphire substrate with chemical solution method (CSD) and radio frequency deposition method (RF), respectively. Morphological characteristics are revealed by SEM graphs. And the result shows that MCN films acquire better crystalline properties and compactness than MCN bulk materials. To verify the excellent features for infrared detection, detectors sized 1mm2 × 0.17 μm and 1 mm2 × 0.33 μm are fabricated based on MCN-RF and MCN-CSD films, respectively. The excess noise at 11 Hz for each detector has been tested and the Hooge's parameters have been calculated. The MCN films obtained by RF deposition and CSD method both show γ/n value of about 2×10-21 cm3, an order lower than bulk MCN and amorphous silicon, which indicates great potentials in integrated infrared detection.
The influence of precursor films on CIGS films prepared by ion beam sputtering deposition
Jun Zhao, Ping Fan, Guangxing Liang, et al.
The CuInGa(CIG) precursor films were grown by ion beam sputtering continuously CuGa/CuIn and CuIn/CuGa, and then selenized CIG to fabricate CIGS absorber films on molybdenum substrates . They were annealed in the same vacuum chamber and under the same temperature (500°C). The CIGS thin films were characterized with X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) in order to study the microstructures, composition, surface morphology, electrical properties, respectively. The results showed that the CIGS thin films appeared smooth and compact with a sequence of Mo/CuGa/CuIn/Se, which were mainly of chalcopyrite structure. The CIGS thin films got the strongest diffraction peak intensity and were with good crystalline quality.
Investigation of Se supply for the growth of CZTSSe thin films for photovoltaics
In this work, the selenization growth of Cu2ZnSn(SxSe1−x)4 (CZTSSe) films was optimized by two groups of experiments in vacuum chamber. The selenization of CZTSSe is strongly dependent on the Se supply in the vacuum chamber. Insufficient Se supply left the selenization incomplete. Higher Se supply to CZTSSe either by increasing the Se powder usage or by increasing the external pressure resulted in the degradation of CZTSSe films with lower degree of crystallinity.The characterization of XRD, Raman and SEM confirmed the films obtained under the best conditions were well-developed CZTSSe films with compact faceted grains and good crystallinity. Additionally, theCZTSSe film grown using 500°C showed more orientation along (220).
Microstructural characterization of Bi2Te3 thin films prepared by hot wall epitaxy
Jianhua Guo, Huiyong Deng, Gujin Hu, et al.
The influence of growth conditions on the microstructures of Bi2Te3 films grown on (111) and (100)-oriented GaAs substrates by hot wall epitaxy is investigated using X-ray diffraction, scan electron microscopy, energy dispersive spectrum, high resolution transmission electron microscopy and micro-Raman spectroscopy. It is found that high quality Bi2Te3 thin films with c-axis oriented are prepared when the temperatures of the Bi2Te3 source and (111) GaAs substrate are 505°C and 375°C respectively. The low substrate temperature and the crystal symmetry mismatch between the (100) GaAs substrate and Bi2Te3 epitaxial film make the crystalline grains mis-oriented, which are responsible for the degradation of the crystal quality of Bi2Te3 films. In addition, the low substrate temperature could lead to the non-stoichiometry.
Fabrication and performance of uncooled infrared bolometer based on Mn1.56Co0.96Ni0.48O4 thin films
Ouyang Cheng, Wei Zhou, Jing Wu, et al.
Mn-Co-Ni-O bolometer with spinel structure has been extensively studied as a low resistivity and high sensitivity negative temperature coefficient material for decades. In this paper, the fabrication process and the performance of uncooled infrared bolometer based on Mn1.56Co0.96Ni0.48O4 (MCNO) thin films grown on Al2O3 substrate by chemical solution deposition were investigated. The MCNO bolometer sized 300×160 μm2 were fabricated by photolithography process followed by wet etching, and the temperature coefficient of resistance reaches -3.81 %K-1 @296 K. Relatively low excess noise was achieved due to the good quality of fabrication process, and the normalized noise power γ/n was found to be 1.8×10-21 cm3 at 296 K. Through black coating the performances for MCNO bolometer, operating at room temperature, are greatly improved and exhibit responsivity of over 354 V/W, detectivity of approximated 4.5×107 cmHz1/2/W@10Hz at ±16 V, and the thermal time constant of about 18 ms. These experiment results indicate that the infrared detection ability of MCNO thin film bolometer is significantly enhanced comparing with bulk devices.
New research progressing of surface modification of medical 316L stainless steels
Lin Xu, Dechun Ba, Qing Wang, et al.
316L stainless steels are widely used in clinical and medical fields because of their comprehensive performance. This paper analyses the current development situation and major existing problems of medical 316L stainless steels. The new methods and research achievement of surface modification in recent years are described in detail. It indicates that surface modification is an effective way to solve clinical application problems, and provides new opportunities for medical 316L stainless steels in medical applications.
Study on growth optimization and metallization of AlN thin films
Zhen Liu, Bin Zhang, Tao Zhu, et al.
Aluminum nitride (AlN) thin films were prepared by reactive magnetron sputtering on silicon substrate with AlN nano seed crystals in argon and nitrogen gas mixtures. The influences of the deposition parameters (pressure, ratio of argon to nitrogen, sputtering power) on the transmittance and structure of the AlN thin films were investigated. X-ray diffraction (XRD) analysis showed a preferred orientation of the AlN (100). The results also showed the optimal condition for AlN growth, i.e. 0.6 Pa for working pressure, 4:1 for nitrogen/argon ratio and 300W for sputtering power. Since copper could not be adhesive to AlN for heat-sink applications, titanium layer was inserted between AlN and copper as a transition layer to achieve the metallization of AlN. We found that the films with titanium layer had obviously better adhesion property, as compared with the films without titanium layer.
Solution to wafer edge silicon needle defect of deep trench process
Jun Guan, Lu Huang, Weimin Shi, et al.
In design and manufacturing of power MOS microelectronic device, deep trench process is used for some special request. The trench depth reaches to scores of micrometer. some are often used in deep trench etching step. Wafer edge generates silicon grass defect. It becomes the major source of particle during the post wet clean steps, which impact line yield and contaminate wet etching tools. The paper introduces two solutions for solving this defect by optimizing trench-photo process. One is inverted trapezoid process and the other is negative resist process. Both solutions in lithography are aimed at wafer edge protection. The deep trench etching step is to protect the underground material from being damaged, and results to solve the wafer edge silicon grass defect of deep trench process.
Rectifying properties and colossal magnetoresistance in La0.9Hf0.1MnO3 /Nb-0.7 wt%-doped SrTiO3 heterojunction
Lin Wang, Zhenping Wu, Yucheng Jiang, et al.
A heterojunction with good rectifying properties in a wide temperature range from 20 K to 300 K was fabricated simply by depositing an as-grown La0.9Hf0.1MnO3 (LHMO) film on a commercial 0.7 wt% Nb-doped SrTiO3 single crystal substrate using pulsed laser deposition technique. The current-voltage behavior of the LHMO/STON is measured under applied magnetic fields varying between 0 and 5 T. The heterojunction shows a remarkable magnetoresistance which depends on both the temperature and bias voltages. The sign of the magnetoresistance as function of temperature at either forward or reverse bias voltage is extensively studied by the filling of electrons in the eg and t2g band. The good rectifying behaviors, the magnetic tunable properties and the maximum magnetoresistance obtained at room temperature make this simple heterojunction promising for practical applications.
Super capacitance properties of SnO2 coated nickel/silicon microchannel plates
Keshuang Hui, Yiping Zhu, Shaohui Xu, et al.
Supercapacitor is achieved by combining tin oxide with three dimensional silicon microchannel plates (Si-MCPs) deposited with nickel film. Electro deposition is applied to deposit the tin oxide on the Ni/Si-MCPs structure followed by sintering at 450°C. The structure and morphology of the samples are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties are investigated in 1 M Na2SO4 solution by cyclic voltammetry, galvanostatic charging-discharging, and electrochemical impedance spectroscopy. The highest specific capacitance of 0.814 F/cm2 (171.37 F/g) is achieved from the sample deposited for 2 h followed by sintering for 2 h.
Characterization of SnO2/Ni/SiO2-MCP anode in three-dimensional lithium-ion battery
Xuefeng Lou, Shaohui Xu, Yiping Zhu, et al.
By combining a SnO2 thin film with silicon dioxide microchannel plate (SiO2-MCP), a three-dimensional (3D) structure with enough space to accommodate the volume change of SnO2 during charging-discharging is produced by MEMS and electroless deposition. Owing to the special structure of the MCP, the battery is able to deliver a reversible Li storage capacity of 408 mAhg-1 after 100 cycles. If the current density is reduced to 200 mAg-1 at a constant current during charging and discharging, the battery exhibits reversible capacities of 1575 and 996 mAhg-1 in the first discharging and charging cycle, respectively. However, a reversible Li-storage capacity of only 298 mAhg−1 is obtained after 50 cycles of deep charging at a current of 200 mAg−1. It is found that silicon is involved in the charging-discharging process at a low current.
The characterization of CuInSe2 thin films by a sequential processes of sputtering and selenization
Jun Zhang, Hongmei Deng, Pingxiong Yang, et al.
Ternary CuInSe2 (CIS) thin films were deposited on glass substrates using a binary CuIn alloy target and an elemental Cu target by employing radio-frequency (RF) magnetron sputtering process and post-selenization process. The selenization procedure is carried out within a partially close-spaced graphite box. The Cu content in CIS thin films can be controlled by different sputtering time of Cu target. The result of energy dispersive X-ray spectroscopy (EDX) indicated that the CIS thin film prepared by single CuIn alloys target had significantly composition deviation. Combined with the X-ray diffraction (XRD) and Raman spectra results showed that all CIS thin films have chalcopyrite structure. Further transmission spectra demonstrated that the optical band gap of CIS thin film is about 1.0 eV.
The study of secondary electron collaborative plasma in the surface modification of PET film
Di Zhang, Hongying Zhou, Ying Guo, et al.
A systematic study of secondary electron collaborative the radio-frequency (RF) inductively coupled plasma (ICP) surface modification of PET film and its surface physical and chemical changes were analyzed. It was found that with a secondary electron collaborative the RF plasma, the contact angle was reduced to 17 ° in 5 seconds and RMS roughness is enhanced by 7 times higher than that of only plasma treatment film. The atomic force microscopy (AFM) and X-ray photo electron spectroscopy (XPS) were employed to investigate the surface characteristics with the collaborative plasma treatments. The amount of oxygen-containing polar functional groups was also elevated with the plasma treatment. Both the enhancements of surface roughness and oxygen-containing functional groups explain the improvements of hydrophilicity and cohesiveness achieved on PET film by the collaborative plasma.
Preparation and properties of low-cost graphene counter electrodes for dye-sensitized solar cells
Qishuang Wu, Yue Shen, Qiandi Wang, et al.
With the advantages of excellent electrical properties, high catalytic activity and low-cost preparation, Graphene is one of the most expected carbon materials to replace the expensive Pt as counter electrodes for dye-sensitized solar cells (DSSCs). In this paper, graphene counter electrodes were obtained by simple doctor-blade coating method on fluorine tin oxides (FTOs). The samples were investigated by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope (SEM). Then the low-cost graphene electrodes were applied in typical sandwich-type DSSCs with TiO2 or ZnO as photoanodes, and their photoelectric conversion efficiency (η) were about 4.34% and 2.28%, respectively, which were a little lower than those of Pt electrodes but much higher than those of graphite electrodes. This law was consistent with the test results of electrochemical impedance spectroscopy (EIS). Low-cost graphene electrodes can be applied in DSSCs by process optimization.