Proceedings Volume 3359

Optical Diagnostics of Materials and Devices for Opto-, Micro-, and Quantum Electronics 1997

Sergey V. Svechnikov, Mikhail Ya. Valakh
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Proceedings Volume 3359

Optical Diagnostics of Materials and Devices for Opto-, Micro-, and Quantum Electronics 1997

Sergey V. Svechnikov, Mikhail Ya. Valakh
View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 20 April 1998
Contents: 10 Sessions, 93 Papers, 0 Presentations
Conference: International Conference on Optical Diagnostics of Materials and Devices for Opto-, Micro-, and Quantum Electronics 1997
Volume Number: 3359

Table of Contents

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Table of Contents

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  • Absorption and Reflection Methods
  • Posters: Absorption and Reflection Methods
  • Interferometry and Nonlinear Optics Methods
  • Posters: Interferometry and Nonlinear Optics Methods
  • Luminescent Methods
  • Posters: Luminescent Methods
  • Raman Scattering
  • Posters: Raman Scattering
  • Optical Materials and Equipment for Nondestructive Testing
  • Posters: Optical Materials and Equipment for Nondestructive Testing
Absorption and Reflection Methods
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Monitoring the aging of high-power laser diode arrays
Jens Wolfgang Tomm, A. Baerwolff, Christoph Lienau, et al.
Different diagnostic methods were investigated in order to evaluate their potential as aging sensitive tool for the analysis of high-power laser diode arrays. The well-known method of photocurrent spectroscopy, i.e. the measurement of the spectral sensitivity of a laser diode acting as a detector, was found to monitor aging properties of high power laser diode arrays in a convenient way. Photocurrent spectra of high power laser diode arrays emitting at 808 nm (1.53 eV) were investigated in the 0.8 - 3.0 eV photon energy range. Aging induced changes in different spectral regions reveal the influence of difference mechanisms affecting the structure. One aging effect--the growth of the defect concentration within the optically active layers of the devices--is monitored. Conclusions on the microscopic nature of the changes are drawn and several applications are discussed.
Femtosecond evolution of semiconductor microcavity modes
Evgenyi A. Vinogradov, A. L. Dobryakov, V. M. Farztdinov, et al.
Dynamics of semiconductor microcavity modes in ZnSe- metal structure was investigated by femtosecond pump- supercontinuum probe spectroscopy in wide spectral region 300 - 800 nm. The powerful laser pump pulse excites electrons of metal (i.e. boundary of the microcavity) and of ZnSe layer (by two-photon absorption and absorption of second-harmonics generated photon). Photoinduced changes of dielectric function of metal transform the boundary condition. It leads to shift of frequencies of cavity modes to red region of spectrum. Another contribution to change of boundary condition is connected with tunneling of excited electrons through Schottky electron barrier into ZnSe layer. The generation of coherent phonon oscillations (LO-phonon mode 250 cm-1 and TO-phonon mode 200 cm-1) in ZnSe was detected.
Optical characterization of Fe- and Cu-doped SiO2 glasses prepared by the sol-gel method
Juan Francisco Perez-Robles, Francisco Javier Garcia Rodriguez, Jesus Gonzalez-Hernandez, et al.
The SiO2 glasses obtained by the sol-gel process, doped with Fe or Cu and annealed either at oxidizing or at reducing (CO - CO2) atmosphere, exhibit deep coloring caused by the absorption and scattering bands in the visible spectral region followed by a considerable change of the shape of the infra-red absorption bands in the region 1000 - 1250 cm-1 corresponding to the optical phonon's excitation. An analysis is made of the spectra obtained by the optical and photoacoustic as well as by the Raman techniques; results are compared with the theory taking into account the light absorption and scattering for the visible region and the influence of the phonons' scattering on the shape of the corresponding absorption bands for the infra- red region. We found that the coloration caused by the annealing of the doped glass at 100 degree(s)C is basically due to the individual Cu and Fe ions in interstitial sites. After annealing at 300 degree(s)C and higher temperatures in oxygen atmosphere the doping atoms enter substitutionally for Si; part of them form colloidal particles of the corresponding metal oxide. The latter exhibit both absorption and scattering which determine the glass color. Annealing under reduction conditions leads to the formation of Cu and Cu2O particles producing a deeper coloration; interaction of the former particles with carbon (graphite) coating causes a specific changes in the Raman spectra which could be attributed to the SERS - Surface Enhanced Raman Scattering.
Laser radiation action on c-Si with dislocations and their diagnostics
Vladimir Arsenovich Makara, L. P. Steblenko, V. A. Pasechny, et al.
The development of new technique of measurement of optical constants of the surface of solid states is carried out. It is shown that two-beams interference method of refraction index distribution measurement has a lot of advantages to a well-known ellipsometric technique. Optical reconstruction of inhomogeneities picture at the surface of c-Si is shown.
Optical properties of thin Al films studied by ordinary and polariton spectroellipsometry
Igor A. Shaikevich, Pavel V. Kolesnik, Victoria Pas'ko, et al.
The new technique of measurements of the ellipsometric parameters and the optical constants of the thin metallic films with excitation of surface polaritons by Kretschman method is elaborated. It is shown that unlike the some authors' opinion both the excitation of the polaritons on the opposite to the illuminated side and the detection of the polaritons are possible for the film with thickness less than 30 nm.
Posters: Absorption and Reflection Methods
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Fullerene-embedded Langmuir-Blodgett films probed by spectroscopic ellipsometry
Eugene G. Bortchagovsky, Igor A. Yurchenko, Zoya I. Kazantseva, et al.
This work presents the first results of ellipsometric investigation of fullerene embedded Langmuir-Blodgett films on gold with surface plasmon excitation. In contrast to the standard ellipsometry, the spectrum of the delta angle obtained in such way has pronounced peculiarities at the C60 optical transitions. Obtained data unambiguous exhibit dependence of electromagnetic response of the system of interest on the proximity of fullerene to the gold surface.
Optical properties and structure of porous silicon
V. S. Stashhuk, V. B. Shevchenko
The structure of porous silicon (PS) layers prepared in different conditions have been studied using the reflection spectroscopy. The HF post-anodization treatment was used to modify the PS structure and properties. It is found that there is a transparent film with a sharp interface above the PS layer on the samples that show an intense photoluminescence. The transparent surface layer thickness as well as the refraction indices of this layer and PS layer below it have been determined. The volume fractions of the oxide and silicon in the surface and lower PS layers have been estimated using the Lorentz-Lorentz and Maxwell-Garnet formulas.
Aging of elements of the integral optics and light guides
Georgii E. Chaika, V. N. Malnev, M. I. Panfilov, et al.
We consider excitations of the electron subsystem when the electromagnetic radiation passes through elements of the integral optics and light guides. The excitation results in the formation of point and finite defects. They change the system index of refraction and cause an additional light scattering.
Influence of different types of surface treatment on photoelectric and optical properties of CdTe crystals
Alia Baidullaeva, Peter E. Mozol', Aleksandr I. Vlasenko
It was investigated photoconductivity (PC) and light absorption spectra of CdTe monocrystals under different types of surface treatment. It was shown that in mechanically polished and plastic deformed crystals PC and absorption edge were determined by broken layer introduced under surface treatment. Also, the role of dislocation in formation of absorption edge and PC spectrum was established and discussed.
Investigation using MAI ellipsometry of damage by surface metallic doping of near-surface layers in semiconductors
Nikolas L. Dmitruk, Lubov A. Zabashta, Oleg I. Zabashta
Flllpsometr is the most preferable method for investigation and characterisation iii faint niicrorelief surtace ss hen other optical methods are not enough sensitive: for example. there is the gentlr sloping surfaces far which so-called Raleigh condjtion is satisfied: 2k5coso 2. k=rt. 2. Here w is the wave length. d is the root-mean-square roughness. Phsicall it means that intuence of the individual roughness is small bitt the total contribution in the optical properties is large. Such type of semiconductor surfaces can he prepared b means of surfaces metallic doping with fallowing removal of metal coating. The electrochernical technology of surface doping (metallization is accompanied surel br dissolution of the semiconductor substrate around the metal islands. Keywords: ellipsometr. multilaer flim. interfactal layer. superlattice. optical properties. theory of the effectise medium
Structure and optical parameters of the system with porous silicon: ellipsometric study
Volodymyr A. Odarych, Oleksandr I. Dacenko, Mykola S. Boltovec, et al.
The principal angle-of-incidence (Phi) and ellipticity tg(rho) of the light reflected from PS surface are measured in the visible on two samples by spectroellipsometry methods. The dependence of the reflected light intensity in the s-plane and ellipsometric parameters on the angle-of-incidence and photoluminescence spectra excited by a pulsed nitrogen laser are recorded as well. An increase of the photoluminescence intensity in storing the sample in the atmosphere and corresponding change of the ellipsometric curves are detected. The obtained evidence indicate the formation of a two-layer structure during electrochemical etching of silicon, the outer layer being transparent and supposedly consisting of silicon compound with nanocrystalline silicon residuals, while the inner one being the layer of porous silicon whose pores are filled with the same compound. Assuming that the compound is silicon dioxide, we have determined the fraction of silicon in the outer layer. The layer refraction index and thickness are determined. It is established that the photoluminescence is more intense in the sample regions with thicker outer layer.
Effect of lateral inhomogeneity of barrier height on the photoresponse characteristics of Schottky junctions
Zsolt J. Horvath, Vo Van Tuyen
The effect of lateral inhomogeneity of Schottky barrier height on the photoresponse characteristics is simulated for normal and lognormal laws of Barrier height distribution. It is obtained that the photocurrent increases while the evaluated apparent Barrier height decreases with the measure of inhomogeneity.
Optical study on microstructure of laser-deposited Si-containing films
Sergey V. Svechnikov, E. B. Kaganovich, E. G. Manoilov, et al.
Optical properties of films obtained by reactive pulse laser deposition of monocrystalline Si have been studied. Transmissivity and reflectivity of these films were measured and used for calculation of their optical constants spectra. The dependencies of the spectra on reactive gas composition and pressure during sputtering let to conclude that the films prepared are composite structures containing at least two phases: SiOxNy matrix and nanocrystalline Si- particles embedded in it.
Absorption diagnostics of quantum size effect on the excited states of SbI3 clusters in FAU zeolite
Sergij V. Virko, Fedir V. Motsnyi, German M. Telbiz
We report the absorption spectra (at 10 K) for SbI3 clusters with molecular numbers 1/2, 1 and 2 which were created in FAU-zeolite cages. At 2.0 - 3.7 eV there appear bands whose energies strongly depends of the loading densities of SbI3 molecules. These energies are remarkable blue shifted compared with the one of the bulk exciton (2.615 eV). This shift is interpreted in terms of the quantum size effect. The observed blue-shift of absorption bands coincides with one calculated in mh/me>>1 approximation (typical for MI3 layered crystals).
Infrared spectroscopy of luminescent porous silicon
Vladimir Arsenovich Makara, V. S. Stashhuk, V. B. Shevchenko
The photoluminescence (PL) and infrared (IR) absorption spectra of porous silicon prepared in different conditions have been studied. HF post-anodization treatment was used to modify the porous silicon properties. It is shown that the samples obtained at higher current density show more intense visible PL. It was also found that there is a correlation between the intensity of luminescence peak and that of IR- absorption peaks related to the Si-O-Si and O3-Si-H modes. The obtained results suggest that surface complexes related to oxygen or hydrogen with oxygen are responsible for the intense visible PL in the samples of porous silicon subjected to HF treatment and exposed to the ambient air.
IR reflection spectra of the ZnO/Al2O3 structure
Evgenie F. Venger, A. V. Melnichuk, Y. A. Pasechnik, et al.
The textured zinc oxide layers on sapphire, prepared by plasma chemical vapor deposition, were investigated with IR reflection spectroscopy in the residual rays region. A computer analysis of variance was used to simulate the reflection spectra of the structure studied and to calculate both charge carrier concentration and mobility in the zinc oxide layers.
Optical properties and electron zone structure of AnXO4 single crystals
Yuri A. Hizhnii, Sergiy G. Nedelko
A possibility of application of the Harrison's modification of the Linear Combination of Atomic Orbitals method to the set of crystals AnXO4 (n equals 1,2; A equals K, Pb; X equals W, Cr S) and to molecular clusters CrO42- is investigated. Calculation of energetic structure for lead tungstate and regular chromate anion and it's comparison with experimental data allowed to determine the values of semiempiric parameters, suitable for calculations by Harrison's method for complex crystals. Energy calculations are carried out for deformed CrO42- clusters, for potassium chromate K2CrO4 and for isostructural to it potassium sulfate K2SO4 in order to clarify the crystal surrounding influence to the CrO42- molecular complexes energy levels and also to arrange the genesis of energy zones.
Mechanism of the ZnGa2S4 monolayer formation on an NaCl surface
N. Popovich, V. Zhikharev, N. I. Dovgoshej, et al.
The calculations are carried out by the use of semiempirical methods of molecular orbital local combination of atom orbital. The calculations results show that Zn will deposit more probable on interstitial sites on 1.5 angstroms distances from the substratum surface with 0.3 eV bond energy, and its position is energetically instable. For Ga atoms, beside interstitial sites (r0 equals 0.5 angstroms, E0 equals -2.3 eV) there are NaCl lattice sites and bond center (r0 equals 1.5 angstroms, E0 equals -1.8 eV). The S atoms will trap by the crystalline lattice sites with 5.0 - 5.5 eV bond energy at 2.5 angstroms distance. Moreover, its penetration to monolayer surface through interstitial sites at r0 equals 4 angstroms distance is possible. In spite of Zn at ZnGa2S4 compound sputtering evaporates the most effectively, the probability of its deposition in the first layer on NaCl substratum is low. Ga and S atoms will substitute Zn atoms, which transit inside lattice or to the next monolayers. The Ga2S structure formation with S localization on sites and Ga in interstitial sites of NaCl lattice is expected.
Optical and photoelectrical studies of strain fields in semiconductor crystals
Boris K. Serdega, V. G. Zykov, Galina N. Semenova, et al.
For some semiconductor crystals and structures the intrinsic mechanical stresses due to the nonuniform dopant distribution were investigated. p-Ge crystals with layered nonuniformities, Si wafers and Ge - GaAs heterostructures served as model samples. Using the birefringence signal measurements, a correlation was found between the dopant distribution and the intrinsic deformations stemming from them. The spectral characteristics of the Ge - GaAs heterostructures indicate at the presence of (oppositely oriented) dopant concentration gradients along the interface in Ge film and GaAs substrate. Using a combination of the optical and photoelectrical measurements enhances the possibilities for the interpretation of the experimental results and also provides a basis for developing nondestructive control methods.
Refractivity dispersion in glassy As2S5 for infrared optics
Ivan Rosola, Alexander A. Kikineshy
The prism method was applied to the refractive index investigations for glasses in their transparency domain. The experimental values of the refractive index were described by means of the Sellmeyer formula and Herzberger pentanomial. The fitting coefficients were determined to estimate the zero-dispersion and dispersion value for these materials in their domain of transparency.
Optical methods of control and characterization of materials for infrared detectors
Yuri V. Vorobiev, Jesus Gonzalez-Hernandez, Martin Yanez-Limon, et al.
A brief review is made of some classic and novel experimental techniques allowing the determination of the main parameters of semiconducting materials with the application of purely optical excitation. Among them some modifications of the photothermoacoustical method (in particular, with the pulse excitation), plasma reflection, sample scanning with the intense light beam.
Ellipsometric probing of metallic mirrors with modified surfaces
Leonid V. Poperenko, Vladimir S. Voitsenya, M. V. Vinnichenko
Optical characterization of the Cu2+, Al2+ and Cr2+ ions implanted copper, aluminum and stainless steel mirrors respectively as well as the stainless steel mirrors with boron coatings was carried out by multiple angle of incidence ellipsometry. Both implanted and nonimplanted areas for aluminum, copper and stainless steel mirrors was then sputtered and probed. Changes of the optical properties of the stainless steel samples after bombardment by Cr2+ would occur due to the formation of a carbon layer on a mirror surface after the implantation, without modification of a microstructure of the surface. In case of the copper mirrors, irradiated by Cu2+ ions and aluminum mirrors implanted by Al2+ ions, the changes of optical parameters would be associated with modification of the subsurfaces layers' microstructure. The optical parameters and thicknesses of boron films on the stainless steel substrate were determined and were 7.3 nm and 16.8 nm respectively.
Interferometry and Nonlinear Optics Methods
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Nonlinear-carrier-transport-governed nonresonant optical nonlinearity in A3B5 crystals
Kestutis Jarasiunas, Liudvikas Subacius
A brief survey is given of recent investigations on non- linear optical phenomena and nonstationary hot carrier transport in III-V crystals for the case, when photoexcited carriers are non-uniformly heated by strong external microwave or dc electric field. We analyze numerically and experimentally a novel possibility to create very efficient and fast electro-optic refractive index modulation. A transient high-field domain grating develops via hot carrier transport at non-resonant interaction of light with bulk GaAs and InP crystals. Time-resolved carrier and field dynamics in picosecond and nanosecond time domain is studied, varying the external dc or microwave field strength, frequency, grating period, and interference field modulation depth. We present the criteria for high-field domains formation, and compare the strength of free-carrier and electro-optic nonlinearities. Light triggered Gunn- domains grating formation is confirmed experimentally by an enhancement of light self-diffraction efficiency in external microwave field.
Measurement of dispersive properties of optical materials and mirrors using spectrally resolved white-light interferometry
Zsolt Bor, Attila P. Kovacs, Karoly Osvay, et al.
We present a simple, accurate and inexpensive interferometric technique based on the spectrally resolved white-light interferometry to determine the group-delay dispersion of optical elements, such as laser crystals and multilayer mirrors. Due to the different dispersion properties of these elements, different evaluation methods of the interference fringes are used for the mirrors and crystals. The reproducibility of our measurements is +/- 5 fs2 and +/- 3% for mirrors and crystals, respectively, with high spectral resolution over a broad spectra range (700 - 900 nm). These dispersion data are important for the construction of compact femtosecond solid-state lasers.
Posters: Interferometry and Nonlinear Optics Methods
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Random electric fields and coherent phonon excitation in C60 films by femtosecond laser pulses
V. M. Farztdinov, S. A. Kovalenko, A. L. Dobryakov, et al.
The ultrafast relaxation of excitations in a C60 thin film was probed in the energy range 1.6 - 3.4 eV by pump- supercontinuum probe technique with 40 fs time resolution. The relaxation rate shows pronounced spectral dependence with maximum at 2 eV in the region of photoinduced darkening and at 2.4 eV in the region of photoinduced bleaching. It is found that the ultrafast relaxation rate decreases with increasing pumping pulse intensity. The shape of the optical density variation at zero time delay in the region of interband transitions at 2.3 - 3.4 eV is similar to the shape of the second derivative of the stationary absorption spectrum. We propose that this may indicate the creation of a random electric field in the sample during the absorption of the pump pulse. We suggest that the decrease of the relaxation rate with the increase of pumping pulse intensity results from extra-heating of the carriers in hu and t1u bands due to internal conversion from higher excited states, which are populated by two-step photon absorption of the intense pump pulse. Coherent excitation of phonons in the 60 - 300 cm-1 frequency range were detected over a wide spectral probe range. An oscillation with a frequency of 118 cm-1 indicates that the nonequilibrium dimerization of C60 molecules takes place following optical excitation. The full splitting of the Hg(1) intramolecular oscillation mode is observed clearly, which demonstrates that a strong deformation of the molecules upon photon absorption takes place.
Direct study of nonequilibrium carriers near Fermi level of Au film by optical reflection and transmission in femtosecond scale
A. L. Dobryakov, Yurii E. Lozovik, V. M. Farztdinov, et al.
The new method of investigation of Fermi surface and Fermi liquid behavior by femtosecond laser spectroscopy is considered. The method consists in study of spectral dependence of the nonequilibrium charge carriers relaxation time by pump-supercontinuum probe technique. Photoinduced optical properties and relaxation of nonequilibrium charge carriers in Au film in a femtosecond time scale are analyzed. It is shown that the relaxation rate sharply slows down in the spectral area related to optical transitions into the vicinity of Fermi level. The form of the peak gives an information on damping of the quasiparpicles near Fermi surface and on deviation of thermalization of nonequilibrium electrons from the conventional equilibrium Fermi-liquid behavior. Studying of ultrafast relaxation time of electron response provides the direct method of investigation thermalization of nonequilibrium electrons in real femtosecond time scale and may give the unique information about deviations from conventional Fermi liquid behavior by femtosecond laser spectroscopy.
Adjustment of optical properties of nonlinear composites by an external electrical field
Leonid G. Grechko, O. A. Davidova, V. N. Malnev
We study the effective dielectric permittivity of composite materials consisting of a metal fraction and the nonlinear dielectric fraction of the type depending quadratically on the external electric field. The two- and three-component composites are considered. It is found that the optical transience of thin film of such composites can be changed from zero up to 40% when applying moderate electric fields.
Role of growth defects on carrier dynamics: semi-insulating GaAs
Vygantas Mizeikis, Kestutis Jarasiunas, Jurgis Storasta, et al.
Using transient light-induced grating experiments, we demonstrate important consequences of interaction between photoexcited electrons and EL2 centers in semiinsulating GaAs at room temperature. Carrier lifetime is found to depend on the local density and ionization ratio of the EL2 centers. A substantial slow down of diffusive grating decay due to the interaction between electrons and photoionized EL2 donors is observed.
Luminescent Methods
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Visible luminescent Si nanocrystals: optical characterization and application
Sergey V. Svechnikov, E. B. Kaganovich
Following the recent study on optical characterization and applications of porous silicon, this report provides a review of our research and development of visible luminescent Si nanocrystals with goal to extend functions of Si based materials. We present laser methods for obtaining porous silicon layers and silicon nanocrystalline composite films. Time resolve photoluminescence and optical properties are discussed. The report provides the results of films microstructure control by optical method. We present several examples of multilayers structures applications: lateral coordinate sensitive photovoltaic devices, new irreversible storage media for pulse recording, diffraction gratings, and cold cathode electron emitters.
Identification of electron-hole transitions in short-period GaAs/AlAs superlattices by time-resolved photoluminescence
Vladimir G. Litovchenko, Dmytro V. Korbutyak, Sergiy G. Krylyuk, et al.
Temporal characteristics of the carriers recombination were investigated in different types of GaAs/AlAs superlattices by the time-resolved photoluminescence spectroscopy. The peculiarities of the electron-hole transitions were established for the superlattices studied in the dependence of the superlattice type and the width of quantum well and barrier layers. In particular, the conditions of existence of free and localized on the interface roughness excitons were found.
Basics of luminescent diagnostics of the dislocation structure of SiC crystals
Ivan S. Gorban, Galina N. Mishinova
The result of the studies of dislocation luminescence in SiC crystals are presented in the report. This semiconductor forms great number of polytypes which differs by periodical alternation of cubic and hexagonal layers in basic planes. High probability of periodic pack infringement caused by very little energy of stacking fault leads to variation of dislocation structures in different glide planes of this crystals. Shockly and Frank partial dislocations are sufficiently important. The dislocation luminescence as growth origin so as dislocations included in result of plastic deformation or high temperature annealing. In this case the spectra of dislocation luminescence are the indicators of processes of phase transitions. The influence of impurities on the dislocation luminescence centers is investigated. The models of structure of dislocation centers and the mechanism of radiative transitions are proposed.
Photoluminescence investigation of Dy incorporation into InP during liquid phase epitaxy
Balint Podor, Evgenie F. Venger, Tatyana Georgiyevn Kryshtab, et al.
The low-temperature photoluminescence and x-ray structural investigations of the properties of InP epilayers grown from indium melt with rare earth element dysprosium (Dy) addition are presented. The Dy addition influence on intensity, linewidth and spectral position of the near-band-gap emission and of vacancy-impurity bands at 0.75 - 1.1 eV is reported. The obtained data of the stoichiometry changes in InP epilayers grown with addition of Dy are considered. Low background doping level with free electron concentration below about 1014 cm-3 at the room temperature for InP epilayers was achieved, that witnessed of the Dy strong gettering effect. It was also ascertained that Dy incorporated into the grown layers in various phases forms (like the inclusions) at lowest using concentration (CLDy approximately 0.01 at.%).
Metal-proximity-induced phosphorescence of C60 molecules
Igor A. Yurchenko, E. Burstein, Dung-Hai Lee, et al.
We discuss recent observations of a metal-proximity-induced fluorescence and phosphorescence of C60 molecules and the key roles that are played in the phenomenon by the metal-induced lowering of the symmetry of the molecules, and the exchange Coulomb spin-flipping scattering and virtual electron hopping (superexchange) between the triplet excitons of the C60 molecules and the electrons in the metal, which lead to a mixing of the singlet and triplet excitons. The enhancement of phosphorescence by the mixing of singlet and triplet exciton states via their exchange interactions with the electrons in the substrate should in general also occur for molecules in close proximity to surfaces having atoms or molecules with incompletely filled outer shells.
Effect of disorder on exciton dynamics in cation-substituted ZnxCd1-xS mixed crystals
Serhiy G. Shevel, Volodymyr L. Vozny, Mykola I. Vytrykhivsky, et al.
Time-integrated and picosecond time-resolved excitonic luminescence of cation-substituted ZnxCd1-xS (0 xS1-x system) versus binding by impurities. Tunneling in the range x xS1-x. It is suggested that in cation-substituted ZnxCd1-xS the broadened levels of impurity-bound excitons are involved in tunneling whereas the contribution from the disorder-induced fluctuations of crystal potential is less important than in anion-substituted CdSexS1-x.
Posters: Luminescent Methods
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Luminescent purity diagnostics of ZnSe crystals
Olegh V. Vakulenko, Vladyslav M. Kravchenko, Zinovij Z. Janchuk
The photoluminescence (PL) spectra of undoped ZnSe crystals obtained from the extra pure raw material with the method of vapor transport with the I2 gas as transporter (crystals A), and ZnSe crystals grown from the same raw material with the sublimation method (crystals B), are studied in the region 500 - 1000 nm at T equals 290 and 100 K in an attempt to find the correlation between the growth methods and the PL spectra. The PL was excited with pulsed N2 (337 nm) and continuous wave He-Cd (442 nm) and Ar+ (488 nm) lasers, which made it possible to realize the cases of strong surface, weak surface (band-to-band) and weak bulk (`impurity') excitation, respectively. It is found that in the PL spectra of samples A in the case of band-to-band excitation, except the `red' band at 1.96 eV, a `green' band at 2.3 eV is observed at 100 K, and in the spectra of samples B an IR-band at 1.25 eV is observed (290 K, bulk excitation) which is much more intense than the `red' one and which disappears at 100 K. It is established that the `red' bands with hvm equals 1.96 - 1.98 eV and hvm equals 1.88 eV in crystals A at 290 K, which arise in band-to-band and `impurity' excitation, respectively, have different nature. There is reason to think that the presence of the IR-band in the PL spectra of undoped ZnSe crystals at room temperature and bulk excitation and its vanishing in reducing the temperature, are the evidence for good purity of the material under study.
Light-activated photoluminescence of porous silicon
Mykola S. Boltovec, Oleksandr I. Dacenko, Svitlana M. Naumenko, et al.
Samples of porous silicon (PS) were etched in concentrated hydrofluoric acid. The initial and etched samples were exposed to the air by pairs at room temperature either in the dark or in daylight. In the process of exposition the integrated intensity of photoluminescence (IPL) excited by a nitrogen laser (337 nm) was measured in regular time intervals on all samples. It has been established that when samples are exposed to the light their IPL rises with time, increasing more rapidly in the etched samples than in the nonetched ones. IPL of the etched samples flattened out after several weeks, while that of the nonetched ones-- after several months. IPL of the samples that were in the dark practically did not change with time. It is shown that the rate of IPL rise depends on a degree of ionization of the air where the samples were located. The results obtained confirm the idea that one of the main factors limiting the quantum yield of PS photoluminescence is the nonradiative recombination that results from the presence of dangling bonds which may be saturated by the light-generated air ions.
Acousto-stimulated change of the electrical and photoelectrical properties of CdxHg1-xTe (x=0.2) crystals
Yaroslav M. Olikh, Rada K. Savkina, Aleksandr I. Vlasenko
In this report a review of numerous experimental investigations of electrophysical, photoelectric and structural CdxHg1-x Te crystals properties changes as a result of ultrasound treatment is presented. Influence of peculiarities of ultrasound treatment effect such as dependence on initial crystal physical parameters and ultrasound treatment characteristics (frequency, intensity) are analyzed.
Electroluminescent control technique of dislocation density in GaP
Olexsandr M. Gontaruk, Dmytro V. Korbutyak, Anatoly P. Kudin, et al.
The effectiveness of radiative recombination of GaP light- diode structures, grown by means of epitaxial technique, is determined by deep nonradiative level concentration, which can be changed by irradiation of samples with fast particles or with the help of ultrasonic treatment. Variations of the nuclear particle doses and energies as well as ultrasonic waves allows to find optimal regimes for treatment of crystals, when the influence becomes positive, i.e., an increase in the light-diode quantum yield is observed. In the crystals treated by ultrasonic at low temperatures (77 degree(s) K) a luminescence intensity was found which are synchronous with those of current. The oscillations mentioned are likely to be caused by formation of mobile dislocation domains involved in the creation of dark lines and defects of dark spots. The work emphasizes a crucial role of dislocation networks in the formation of the fields of nonradiative recombination in an ultrasonic-treated sample bulk.
Determination of the concentration of shallow impurities in semi-insulating GaAs by low-temperature (77 K) photoluminescence
K. D. Glinchuk, N. M. Litovchenko, Anatoliy V. Prokhorovich, et al.
The detailed analysis of the low-temperature (77 K) photoluminescence spectra of undoped semi-insulating GaAs crystals containing different concentrations of shallow impurities Zn, C and Si is given. A linear correlation between the reduced intensities of the Zn, C and Si acceptor-induced emission bands and the concentrations of Zn, C and Si atoms is found. As a result the calibration dependences--the ratio of the intensity of the acceptor- induced emission band to the intensity of the near intrinsic emission band as a function of the impurity concentration were obtained. The above tabulated curves could be successfully used for the determination of the concentrations of shallow impurities Zn, C and Si by 77 K photoluminescence spectra measurements in any semi- insulating GaAs crystals.
Luminescence method for the determination of the current injection component in red GaAs1-xPx light-emitting diodes
K. D. Glinchuk, G. A. Sukach
A method is proposed to find the current injection component in red GaAs1-xPx light-emitting diodes at high forward voltages V(V > 1.7 volts), when the flowing current i is mainly the ohmic one. The method is based on the simultaneous measurements of the electroluminescence decay time, electroluminescence intensity vs. the flowing current dependences and current-voltage characteristics. It is shown that in red GaAs1-xPx light-emitting diodes the current injection component j approximately i at low V(V < 1.6 volts) and j approximately j1/2 at high V(V > 1.7 volts). The proposed method for the determination of the j equals $qq(i) dependences is suitable also for other light-emitting diodes based on different semiconductor materials.
Single crystalline imaging plates based on epitaxial and diffusion structures of alkali halide compounds
Ivan V. Konstankevych, Yuri V. Zorenko, M. Batenchuk, et al.
In present work the possibility of use the some alkali halide compounds as storage phosphor for image plates is discussed. For improvement of spatial resolution in digital radiographic systems it is proposed to use the single crystalline image plates prepared by liquid phase epitaxy and by diffusion. The optical luminescence properties of obtained structures are studied. The possible mechanisms of photostimulable luminescence in thin single crystalline KBr:In;Tl, RbJ:Tl, KCl:In;Tl layers are discussed.
Single crystalline thin film screens for cathode ray tubes: possibilities of application, peculiarities, and light parameters
Yuri V. Zorenko, M. Batenchuk, M. Pashkovsky, et al.
In present work the peculiarities of preparing of single crystalline thin films (SCFs) Y3Al5O12 by liquid phase epitaxy technique and its light emission characteristics in different spectral regions are investigated. These films are luminescent screens for cathode ray tubes with high resolution prepared on base of Y3Al5O12 doped by rare-earth and isoelectronic impurities. The advantages of these screens over bulk crystalline and powder analogs have been shown. The possibilities of cathode ray tube application with SCF screen in raster optical microscopes, proectional systems and original devices for processing of color images from PC display (computer slider) are discussed.
Photoluminescent investigations of SHF irradiation effect on defect states in GaAs:Sn(Te) and InP crystals
Irene B. Ermolovich, Evgenie F. Venger, Raisa V. Konakova, et al.
Results of investigations of magnetron and hyrotron irradiations effects on spectra of local states to be formed by intrinsic and impurity point structure defects in nearsurface layers of GaAs:Sn (111), GaAs:Sn (100), GaAs:Te (111) and InP (100) have been studied and discussed. The effect of SHF irradiation on defect states in GaAs and InP has been obtained to depend on both the type of doped impurity and the orientation of sample surface. The important role of intrinsic vacancies in processes of rebuilding point and complex defects in nearsurface layers has been established. The gettering action of SHF- irradiation on point defects and the increase of homogeneity of SHF-irradiated crystals have been found. The mechanisms of SHF-fields and semiconductor compounds interactions are discussed.
Short-wave emission of Tb3+ as an optical indicator of TFELS matrix changes
V. S. Khomchenko, V. E. Rodionov, Yu. A. Tzirkunov
It is shown that short-wave emission of Tb3+ may be using as an optical indicator of thin film electroluminescent structures matrix changes because that emission shows a high spectral response to the crystal field symmetry change near Tb3+ ion. Depending on the conditions of preparation of the film, the annealing temperature, the action of the gamma-ray radiation of the Tb3+ electroluminescent spectra's view corroborates the conclusion. Electroluminescent long-wave part spectra compared with short-wave part spectra at T equals 4.2 divided by 300 K regarding the dependence on film preparation conditions. Such comparisons demonstrate an advantage of using over `green' emission of `violet' emission terbium as an optical indicator.
Diagnostic of the energy level distribution of tetragonal cadmium and zinc diphosphides
Ishtvan V. Fekeshgazi, G. Grischenko, P. Romanyk, et al.
Photoreflection, photo- and cathodoluminescence investigations of the electron energy levels distribution in tetragonal cadmium and zinc diphosphide crystals at 4.2, 80 and 300 K temperatures and light polarizations parallel and perpendicular to optical axis were carried out. The obtained results confirm the calculated data of the band structure of these crystals, that indicate the presence of the complicated energy spectra states and majority different type of two-quantum transitions, provides of high efficiency of nonlinear processes.
Optical diagnostics of light-emitting Si clusters in SiO2 formed by ion implantation
Mikhail Ya. Valakh, V. A. Yukhimchuk, V. Ya. Bratus', et al.
Si/SiO2 structures implanted by Si+ ions are investigated with photoluminescence (PL), electron spin resonance and low frequency Raman scattering (RS) methods. The nature of the PL band at 2.0 eV that appears after implantation is identified. The sizes of Si nanocrystals formed after the implantation and thermal annealing at T equals 1200 degree(s)C are determined by low frequency RS method. It is shown that low temperature plasma treatment of the annealed samples leads to the increase of PL intensity.
Detection of deep boron-involved thermal donor formation in silicon by combined photoluminescent, Hall, and ESR techniques
V. M. Babich, Nicolay P. Baran, V. L. Kiritsa, et al.
The low temperature photoluminescence technique applied together with Hall and ESR methods elucidated the variation of boron doping impurity behavior in Si:B under thermal annealing at 450 degree(s)C. It is shown that boron impurity p-Si is involved in the formation of electrically active complexes, namely, deep single-charge thermal donors.
Chlorine-related photoluminescence of CdTe gamma detector material
P. N. Tkachuk, V. I. Tkachuk, Dmytro V. Korbutyak, et al.
Etching with bromine in methanol of the CdTe single crystals (as-grown and purified by extraction treatments) was performed on the (110) and (111)A surfaces. The crystals have been studied by Auger electron spectroscopy and low temperature photoluminescence. A correlation between results of Auger electron spectroscopy and features of photoluminescence spectra has been found. On the basis model which considers that etching related Cl acts as a non-(Gamma) associated defect the `hot' photoluminescence beyond the fundamental absorption edge of CdTe has been explained.
Luminescence of CdSiP2 crystals
Tsezarii A. Kryskov, Vasyl Golonzhka, Antonina A. Gubanova, et al.
Some general features of the behavior of Cu, Zn, Bi, S, Eu and Mn impurities in CdSiP2 crystals are studied by analyzing photo- and electron beam-excited luminescence spectra measured in a temperature range of 1.4 to 300 K, as well as by determining their electrical parameters. The impurities are established to substitute mainly the cadmium in the crystalline lattice and to promote the formation of complexes of defects, which are radiative recombination centers. Cd vacancies as well participate in the defect complex formation processes. A radiation ascribed to interstitial Cd-type defects, is discovered in CdSiP2 crystals. From comparison with Raman scattering measurements, the direct band gap was evaluated to be 2.42 eV at 1.4 K.
Luminescence of ZnSe(Te) crystals melt-grown from the charge and enriched in selenium
Vladimir D. Ryzhikov, Leonid P. Gal'chinetsky, S. N. Galkin, et al.
The evolution of the radioluminescence (RL) spectra and spectral-kinetic characteristics of ZnSe100-xTex (0.01 <EQ x <EQ 0.96) crystals were studied at 77 K as a function of concentration of metallic Se added to the initial charge. The crystals were grown from the melt under argon pressure. The elemental composition of the samples was checked by x-ray luminescence and chemical analysis. It is shown that, depending upon the degree of doping with Te, different RL bands compete with each other. Thus, at 0.01 <EQ x <EQ 0.20 the short-wave luminescence should be probably treated as a self-activated luminescence band caused by recombination in the complex {V Zn- + D+}, where V is the Zn vacancy, a D-donor. The green-blue luminescence at 0.20 <EQ x <EQ 0.96 can be probably associated with Te clusters, while the formation of the `green' RL band is presumably due to Zn vacancies. The presence of the intense `red' band in ZnSe100-xTex samples, corresponding to the whole range of x, is considered as an indication of the fact that the luminescence center {V Zn- + Te0 + Zn+} comprises the isovalent dopant Te and the excess Zn.
Luminescence of ZnS polycrystals prepared by SSHTS
Yu. F. Vaksman, E. V. Stankova, S. V. Zubritskiy, et al.
The properties of hexagonal ZnS polycrystals prepared by the self-spreading high temperature synthesis have been investigated by the photoluminescence method. The comparison of poly- and mono-crystals emission properties were carried out. The effect of longtime luminescence relaxation in Cl- doped ZnS polycrystals was discovered.
Raman Scattering
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Micro-Raman characterization of GaN epilayers
Marion Renucci, F. Demangeot, J. Frandon
Raman spectroscopy is used to study the influence of the deposition temperature of GaN buffer layers on the lattice dynamics of epitaxial GaN layers. This growth parameter is shown to play a role in the non intentional n-doping of the layers, as evidenced by plasmon coupling with longitudinal phonons. Lineshape analysis of the L-(0) low- frequency component of the coupled A1 (LO)-plasmon mode, based on a dielectric approach and supported by IR reflectivity measurements, is applied to spatially-resolved micro-Raman measurements, revealing local inhomogeneities in the free-carrier concentration on the scale of microcrystallites. On account of polarization measurements achieved on the sample edge, additional scattering in the spectral range of optical phonons is attributed to charge density fluctuations. Partial screening of q does not equal 0 LO phonons by the free-carriers is invoked to explain polarized scattering located in the range of high density of phonon states.
Raman spectra and effects of electrical field and stress in DQW AlGaAs lasers
A. Je. Semjonow
Optical phonon Raman lines (TO-GaAs-like and TO,LO-AlAs- like) are shifted to lower energies and are asymmetrically broadened in electrical field compared with that of AlGaAs without field. Simultaneously are increased the intensities of all (optical and acoustical) Raman lines in electrical field. These increasings are different for different `components' of the optical phonons lines. The most significant amplification of intensities (about 3-times) is observed for the lines which correspond to the layers with Al-concentration x equals 0.3. These experimental results on intensity increasing in electrical field can be described by phonon Cherencov-effect for optical and acoustical phonons. We discuss also the low frequency tail intensity increasing and stress effects and the nature of the second temperature maximum (not at the center of the emitter).
Optical characterization of carbon ion implantation into Si and SiGe alloys
Si and epitaxial SiGe strained and relaxed layers have been implanted with C+ ions to investigate the formation of SiCy and SiGexCy alloys (medium doses) as well as the ion beam synthesis of SiC in SiGe matrices (high doses). These layers have been analyzed by Raman scattering, in correlation with XRD, XPS and TEM. These data show that for implant temperature of 500 degree(s)C (crystalline target), carbon is not incorporated in substitutional sites, and (beta) -SiC precipitates aligned with the implanted matrix are formed. The residual strain and the degree of missorientation of these precipitates depend on the strain, defects and bond length of the implanted matrix. Moreover, precipitation of (beta) -SiC in the implanted region causes an enhanced Ge migration, mainly towards the surface. This determines a Ge enrichment and consequent relaxation of the Si1-xGex matrix. This contrasts with the room temperature implants performed in preamorphized Si layers, where carbon incorporation in substitutional sites (Cs) takes place after thermal annealing. The maximum amount of Cs is found for the implanted dose corresponding to a peak carbon concentration of 1.3%. For higher doses, there is a degradation of the crystal quality of the recrystallized layer.
Thin films for nonlinear optics: sol-gel preparation, Raman and XAS characterization of alpha-Fe2O3
Pier Paolo Lottici, Camilla Baratto, Danilo Bersani, et al.
Films of (alpha) -Fe2O3, whose high non-linear optical susceptibility (chi) (3) has been recently reported, have been prepared by the sol-gel method using two different sol-gel syntheses, both starting from inorganic salts as precursors, Fe(NO3)3-9H2O or FeCl3- 6H2O. Thermal treatments on films obtained by dip coating lead to the (alpha) -Fe2O3 hematite structure for both preparations as indicated by XRD, Raman and X-Ray Absorption Spectroscopy measurements.
Diagnostics of nitrogen-implanted diamond-like carbon films by optical and microhardness measurements
Victor V. Artamonov, Nickolai I. Klyui, B. N. Romanyuk, et al.
Comparative study of nitrogen implanted a-C:H film has been carried out by micro-Raman and nanoindentation techniques. At high dose nitrogen implantation (1(DOT)1017 cm-2) the structural inhomogeneities are observed in the implanted region. After implantation a significant broadening and energy shift of both G- and D-bands in Raman spectra are observed. On the other hand, film hardness measurements reveal the existence of more dramatic differences between both implanted regions with homogeneous and structural inhomogeneities. The film hardness in the inhomogeneous region more than by 5 times exceed the one in the homogeneous region. The hardness improvement of ion implanted a-C:H film is related to film disordering and ion beam induced phase-structure transformation in the implanted region.
Posters: Raman Scattering
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Interface roughness and confined LO phonon modes in (ZnSe)2 (ZnS)11/GaAs(100) superlattices grown by PAVPE
V. V. Tishchenko, Y. S. Raptis, Evangelos Anastassakis
Raman scattering spectra have been measured in (ZnSe)2 (ZnS)11 superlattices (SLs) grown by the photo-assisted vapor phase epitaxy technique. Spectral reveal effects from interface disordering. The magnitude of this disorder was estimated from the observed confinement of the B2 symmetry LO phonon modes in different SL areas with unequal thickness for the ZnSe quantum wells, and was found equal to one monolayer. It has been shown that such estimates are more accurate when based on spectra obtained below resonance.
Raman diagnostics of new types of A3B2X9 layered crystals
Olegh V. Vakulenko, Victor O. Gubanov, Stepan V. Kun, et al.
Vibrational spectra of layered crystals Rb3Bi2Br9, Rb3Bi2I9, Cs3Bi2I9 were investigated by the method of Raman spectroscopy at 293 K and 100 K. The distribution of vibrational modes by symmetric type was considered for molecular ion [B2X9]3-, for layered packet and for the whole crystal. It is shown that the approximate vibrational forms of the molecule B2X9 and the ions [B2X9]3- can be obtained unambiguously using on the symmetry considerations only. The condition is imposed that the vibrational modes in addition to their classification by the symmetry types allow resolution to the quasivalent and quasideformational ones which differ significantly in frequencies. The forms of the normal vibrations of [B2X9]3- are consistent with the vibration forms of the layer packet, whereas the shape of the vibration forms of the given symmetry type for the whole crystal coincides with the shapes of the normal vibration forms of two adjacent elementary packets which have the same or contrary phases. The correlation diagram is built up allows to establish correspondence between the modes of the elementary layer packet and the fundamental vibration modes of the crystal lattice which are combined into the Davydov doublets. The analysis of the obtained experimental results for the A3B2X9 crystals was carried out. It was obtained that at the modification of the chemical composition of the compound by isovalent substitution, the slight change in the vibration forms does not actually effect the power constant, and the frequencies are modified only due to the atoms mass change.
Photostructural transformations in amorphous Ge-S thin films: a light-scattering study
N. V. Bondar, N. A. Davydova, V. V. Tishchenko, et al.
Reversible changes of the Raman spectra by the cycle of band-gap laser irradiation and annealing (storing in the dark) has been observed for amorphous Ge20S80 thin films for the first time. The observed changes in the region of stretch vibrations of the chalcogenide atoms is direct evidence for the occurrence of gross structural changes in local bonding configuration cased by optical irradiation. It has been shown that under the laser irradiation the bonding tendency of the chalcogenide atoms is to form rings rather than chains, i.e. the cis-conformation is preferred over trans-conformation.
Nanostructure of a-C:N films characterized by Raman spectroscopy
Andrey V. Vasin, O. V. Vasylyk, Ludmila A. Matveeva
Amorphous carbon films prepared by nitrogen ions assisted thermal evaporation were analyzed by means of Raman scattering. It was shown that ion bombardment of substrate during carbon evaporation leads to a nanostructure reordering. It was analyzed the changes of Raman spectra characteristics with variation of ion bombardment conditions.
Raman-scattering diagnostics of the structure of hydrogenated amorphous diamond-like carbon films
Mikhail Ya. Valakh, O. V. Vasylyk, A. G. Gontar, et al.
Hydrogenated amorphous diamond-like carbon (DLC) films produced by RF-glow discharge deposition from hydrocarbon mixtures in a parallel diode-type plasma reactor were investigated. The DLC films were obtained at various gas mixture compositions and bias voltages (Vb). Raman spectra of DLC films in the range 1000 - 1800 cm-1 were analyzed. Our results are given in terms of I(D)/I(G) intensity ratio, bands position, and width (FWHM) as a function of bias voltage and gas mixture. The analysis of Raman spectra shows that bias voltage value is critical for the DLC films structure. The increase of Vb from -200 V to -700 V results in the essential high-frequency shift of G- and D-bands and change of their intensities ratio I(D)/I(G) from 0.64 (Vb equals 200 V) to 3.2 (Vb equals 700 V). Similar high-frequency shift, change of FWHM and I(D)/I(G) intensities ratio were observed at the variation of methane concentration in gas mixture composition from 100 to 20%.
Structural peculiarities and phonon spectra of A3B2C9 compounds: a Raman-scattering diagnostic
Mikhail P. Lisitsa, Eugen Yu. Peresh, O. V. Trylis, et al.
In presented work the Raman spectra of the family of ferroelectric crystals A3B2C9, (here A equals Cs, Rb; B equals Sb, Bi; C equals Br) are given and the assignment of some high frequency bands is fulfilled. The conclusion about possible difference of structure of the crystals Rb3Bi2Br9 and Rb3Sb2Br9 from well known and detaily investigated structure of Cs3Bi2Br9 crystal is made. We also suggest that significant variation of spectra in the temperature region 110 - 300 K can be not only due to phase transition effects but also owing to anharmonic Fermi resonance between one- and two phonon excitations.
Optical study of the influence of oxygen on the synthesis of SiC-buried layer in Cz-Si and Fz-Si
V. A. Yukhimchuk, V. P. Melnik, B. N. Romanjuk, et al.
The peculiarities of ion-beam synthesis of buried SiC layers in silicon wafers have been studied by Raman and infrared spectroscopy. The effect of oxygen and mechanical stresses on SiC layer formation has been also investigated. It was shown that compressive stresses and SiO2 precipitates with the size larger than some critical value stimulate nucleation and formation of buried SiC layer.
Optical characterization of As40S40Se20 inorganic resist
Alexander V. Stronski, Miroslav Vlcek, Peter E. Shepeljavi, et al.
The results of investigations of photostimulated phenomena in As40S40Se20 thin films with the help of optical methods are presented in this paper. Raman spectra, optical constants in the transparency region of as- evaporated, exposed and annealed films were obtained. The As40S40Se20 thin films have shown good etching selectivity in amine based (in particular, nonaqueous solutions based on triethylamine) etching solutions.
Use of Raman-scattering waves for the optical diagnostics of semiconductor materials for microelectronics
Olexander Yu. Semchuk, Leonid G. Grechko, Vladimir M. Ogenko, et al.
An investigation has been made of the electric field dependencies of the Raman cross-section for the electromagnetic waves scattered on the fluctuations in nonequilibrium semiconductor plasma for some cases of the orientations of external electric field, wave vector of the fluctuation wave, and the wave vector of falling wave. It has been found that in the semiconductor plasma this cross- section depends to a great extent on an external electric field, the carriers scattering mechanisms, and the energy band structure. It is shown that the analysis of the Raman wave scattering and transformation coefficients may be a very good technique for the diagnosis of the semiconductor materials for the microelectronics.
Diagnostics of noncrystalline films by using interference of Raman signals in thin and superthin films
Vladymyr M. Mitsa
The depth dependence of Raman spectra of a-GeS2-type films having a different optical thickness ((lambda) /4 and (lambda) /2) and their refractive index have been investigated. The model of a layered-inhomogeneous structure of film has been proposed. There have been distinguished: near-surface region (up to 50 angstroms), central part and transition film-substrate region (up to 300 angstroms).
Optical Materials and Equipment for Nondestructive Testing
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Photoacoustic spectroscopy of semiconductor nanoclusters incorporated into various dielectric matrices
Ivan V. Blonskij, Volodymyr A. Tkhoryk, German M. Tel'biz, et al.
A new technique proposed for detection of non-basic phases (percolative semiconductor nanoclusters incorporated into intrinsic cages of zeolites) in samples, which are the mixture of these nanoclusters with crystals of micron size. This technique is based on studying of the photothermal (PhT) spectra obtained by gas-microphone method of signal detection. The main idea consists in taking into account contribution to the PhT response from so-called interstitial gas filling the pores inside samples based on zeolite. The method proposed lets to improve the sensitivity of PhT spectroscopy up to detection of quantum-size phases in the objects of experiment.
Cryogenic spectrometric ellipsometer for studying solid state optical properties
Alla I. Belyaeva, T. G. Grebennik
Cryogenic spectrometric ellipsometer (CSE) for studding solid state optical properties was developed. CSE permits determination of the optical constants of solid in the range between 0.3 and 2 micron, in temperature interval from 5 up to 300 K. CSE is used for bulk samples characterization and thin films including multilayers stacks analysis (refractive indices and absorption coefficients (pseudodielectric functions) and thickness measurement). The special small continuous flow cryostat had been designed for studies in the wide temperature range. The angles of incidence are changed from 45 to 70 degree(s) discretely by the position of the cryostat windows.
New technique for investigation of solar cell sheet resistance distribution by laser beam scanning
Vadym O. Goncharov, Leonid M. Ilchenko, S. Kilchitskaya, et al.
Laser beam scanning was applied for evaluating the distribution of sheet resistance of solar cell emitter. It was shown that the voltage drop around the illuminated spot has an information about the local sheet resistance since the most part of the voltage drop occurs near the illuminated area. The current under local illumination in reverse direction depends on the local quantum efficiency while in forward direction it depends on the same local properties and on the local sheet resistance. The processing of laser beam induced current images at different bias voltage gives a map of local sheet resistance complementing other techniques for investigation the electron devices. We investigated one and dual-beam technique for amplitude and phase LBIC measurement by means of universal laser scanning microscope worked in amplitude and differential-phase regimes. Acousto-optical scanning results in 2D distribution of amplitude or phase LBIC. For convenience of image processing and visualization, TV type scanning is applied to laser beams.
X-ray introscopic digital systems of nondestructive testing based on SELDI detectors
Vladimir D. Ryzhikov, Leonid P. Gal'chinetsky, Alexandr D. Opolonin, et al.
The receiving-detecting unit using scintillator-photodiode type detectors can be a basis for introscopic systems, industrial non-destructive testing instruments, devices for medical and technical tomography, fluorography, etc., have been developed.
Complete diagnostics of pyroactive structures for smart systems of optoelectronics
Svetlana L. Bravina, Nicholas V. Morozovsky
The results of study of pyroelectric phenomena in ferroelectric materials for evidence of the possibility to embody the functions promising for creation of smart systems for optoelectronic applications are presented. Designing such systems requires the development of methods for non- destructive complete diagnostics preferably by developing the self-diagnostic ability inherent in materials with the features of smart/intelligent ones. The complex method of complete non-destructive qualification of pyroactive materials based on the method of dynamic photopyroelectric effect allows the determination of pyroelectric, piezoelectric, ferroelectric, dielectric and thermophysical characteristics. The measuring system which allows the study of these characteristics and also memory effects, switching effects, fatigue and degradation process, self-repair process and others is presented. Sample pyroactive system with increased intelligence, such as systems with built-in adaptive controllable domain structure promising for functional optics are developed and peculiarities of their characterization are discussed.
Optical disk mastering process control methods
Andrey A. Kryuchin, Viacheslav V. Petrov, Semen M. Shanoylo, et al.
Production of high quality master discs used in CD manufacturing process is possible only at light-sensitive material exposure process optic control carrying out and relief image production. High precision of relief image production process control on the master disc surface is provided in case of relief formation in the process of data recording. The results of optical discs mastering using direct reading technology (recording quality control) in the process of recording are considered below. The high- sensitive material composition selection effect upon pit form is given. The conditions in which the light-sensitive layer material is practically completely removed from master disc surface are defined. The after-record direct reading method comparison to the method of image production using photoresists is given.
Posters: Optical Materials and Equipment for Nondestructive Testing
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Random error behavior for rotating-analyzer ellipsometers
The article gives a new approach for the consideration of the precision reachable by rotating-analyzer ellipsometers. Presented results approve all qualitative conclusions of the previous article on this topic, but the general equations and numerical results are different. Additionally this article treats the problem of optimizing the measurements of ellipsometric angles separately. It is shown, measured (Psi) and (Delta) are correlated for such type of ellipsometers. For most real in practice short-noise-limited case a good rule of thumb is proposed, which gives the compromise for suboptimize measurements as (rho) , so (Psi) and (Delta) at the same time. It is proved, as all sources of noise work simultaneously, as well as for null-ellipsometry it is impossible to make measurements at the Brewster angle with rotating-analyzer ellipsometers.
Cd1-xMnxTe/CdyHg1-yTe heterostructures: structure and optical properties
Aleksandr I. Vlasenko, Vladimir N. Babentsov, Z. K. Vlasenko, et al.
A graded gap CdyHg1-yTe layers grown by ISO VPE technique on the Cd1-xMnxTe substrate were comprehensively studied by scanning electron microscope, X ray microanalyzer, IR transmission method. The influence of the initial stage of CdyHg1-yTe layer growth on the defect structure near the geometrical boundary of the substrate was shown. The possible influence of defects on this boundary on the band structure is shown. The possibility of two steps annealing of the photosensitive CdyHg1-yTe layer was demonstrated numerically aiming the decreasing of the residual native donors, namely tellurium untisites concentration.
Oxygen concentration distribution determination in silicon wafers by semiconductor IR laser spectroscopy
Sergey D. Darchuk, Fiodor F. Sizov
IR laser spectral analysis was applied for rapid determination of oxygen concentration and its distribution in silicon wafers at room temperature by the method of scanning semiconductor laser spectroscopy. Pb1-xSnxTe injection lasers, the emitting wavelength of which was changed in the region of (lambda) equals 9.1 micrometers by current impulses of different duration and amplitude, were used. The whole square under an absorption curve to determine the absorption coefficient by all the oxygen complexes and then to evoke the oxygen concentration was taken into account. The possibility to reveal even at room temperature by the method applied the oxygen complexes of different configuration was demonstrated.
Polarimetry of inhomogeneous slab of anisotropic medium
Borys M. Kolisnychenko, Vitalij N. Kurashov, Valeri V. Marienko, et al.
In the paper we investigated both theoretically and experimentally the peculiarities of the interaction between coherent electromagnetic radiation and a slab of inhomogeneous anisotropic media. Theoretical model of the object was based on the approximation of anisotropic phase screen. Measurements were taken with rough anisotropic phase plate in transmitted light. Spatial polarization characteristics of scattered radiation were measured in relation to the polarization parameters of incident light. Experimental results agree satisfactory with theoretical predictions.
Controlling of the state of CoSi2 thin film by laser radiation
Maris Knite, Arthur Medvids
Formation of thin crystalline layers of CoSi2 deposited by coevaporation of Co + Si mixtures on SiO2/Si substrates has been attained by a Q-switched YAG:Nd and CO2 lasers. Electrical and optical properties of the CoSi2 layers have been studied by simultaneous laser irradiation. It is shown that high quality resistive crystalline CoSi2 films can be obtained by treatment with CO2 laser radiation of 2 MW/cm2 to 8 MW/cm2 intensity. Besides, resistance of the layer decreases by a factor of 9. When such a layer is subjected to Q-switched YAG:Nd laser radiation 20 MW/cm2 - 35 MW/cm2 intensity, the magnitude of the resistance increases by a factor of 3 due to forming clusters of vacancies in CoSi2. The CoSi2 phase and rise of concentration of vacancies was determined by x-ray diffraction. It is shown that the change in optical parameters of the resistive film subject to laser treatment can be used for both remote sensing of resistivity and quality check.
Vacuum-thermal-deposited films of organic dyes as sensitive materials in electrodigit visualization processes
J. A. Zhizhenko, Vladimir Enokovich Agabekov, Yu. K. Mikhailovskii, et al.
The method of electrodigit diagnostics is based on registration of a picture luminescence of object, placed in a high-frequency high-voltage field. It lets to reveal surface heterogeneity of a various nature, defects conductor under a layer optical opaque dielectric or in most dielectric. Early it is offered to replace traditionally used in this method halogensilver materials for vacuum thermal deposition (VTD) on dielectric of a substrate by thin layers organic dyes, that will make a method more technological and cheap. In the given work the spectral methods have qualitatively appreciated a role making of (electronic, x-ray, ultraviolet and visible radiations) in formation of the electrodigit image in VTD-films of Rhodamine 6G (R-6G) and dye of a class Oxazine (OX-1). It is established, that: (1) the contribution all making (except UV-radiation) in formation of a drawing in VTD-films of R-6G and OX-1 is insignificant; (2) the visible image in a VTD- film of R-6G will be formed for the account of decomposition of dye by `rigid' UV-radiation; (3) the influence of 1 sec. of the crown discharge on 0,68-micrometers a VTD-film of OX-1 is equivalent of irradiation her 365 nm by a doze 0,8 J/cm2.
Vacuum-deposited dye films and their optical properties
Konstantin P. Gritsenko, Yuri L. Slominsky, Konstantin V. Fedotov
Evaporated squarilium-based, malonitrile-based merocyanine, metal-complexes on dithiolate base, ketocyanine and phtalocyanine (Pc) dyes form smooth films, which show high optical absorption and reflection in visible and near- infrared regions. Co-deposition of polytetrafluoroethylene (PTFE) and Pc dyes showed that the films obtained consist of the PTFE matrix filled by Pc particles of 10 - 30 nm size. Recording on dye film is performed in ablative mode by 9 mW of semiconductor laser, if PTFE sublayer is used. Three types of hole opening mechanisms were obtained by choosing dye and substrate with properties needed.
Characterization of layered structures by photoacoustic piezoelectric technique
A thermoelastic response that arises in a two-layered wafer under its heating by periodically modulated light beam has been studied theoretically. For the case of piezoelectric detection of the signal an analytical expression for the output voltage of the transducer has been obtained which allows to calculate the amplitude and phase characteristics versus modulation frequency. It is shown that these characteristics vary strongly depending on thermal and elastic properties of both layers.
Methods and devices for check-up of content of contamination in liquid media with low absorbability
Olexander I. Bilyi, Vasyl B. Getman, Yaroslav P. Ferensovich, et al.
The demands of purity of liquid media with low absorbability such as photoresist used in microelectronics production of light oil-products are enhanced at present. Particular attention is given to developing of methods and devices for estimation of liquid purity. In this report the methods and the analyzers, developed at Applied Physics Institute of Ivan Franko State University, intended for checking the content of the microparticles larger than 0.3 micrometers in liquid photoresist or light oil-products are considered.
Temperature behavior and the optical damage threshold of holographic gratings based on photopolymerizable materials
Oksana V. Sakhno, Tatiana N. Smirnova, Eugene A. Tikhonov
Results of investigations of diffraction efficiency (DE) temperature dependence and optical damage threshold of volume phase holograms-transmission gratings are presented. DE remains constant in the range +10 < T < +110 degree(s)C for holograms on the base of PPC-488. Changes of DE are reversible in +110 < T < +200 degree(s)C and if T > +200 degree(s)C the irreversible change takes place because of specific cracking of films along phase planes. The reversible change of DE can be described by diagrams of phase balance in the system: polymer-diffusant. Optical damage threshold of under study gratings is defined by the threshold of photo- and thermo-decay of neutral diffusant 1-naphthalene bromide. Different compositions, which contain the diffusant with high threshold of photo- and thermal-dissociation processes have been tested. Some modifications of basic photopolymer composition with the threshold of optical damage more than 200 MW/sm2 were proposed.
Study of optical properties of layered systems by multiangle ellipsometry
Lubov A. Zabashta
The authors discuss the possibility of studying the optical properties of multilayer films using multiangle ellipsometry. The investigation was carried out on W/Si metal superlattice produced by high-frequency sputtering deposition. The effective optical constants nf and kf were analyzed as a function of the superlattice period in the framework of the theory of optical properties of multilayer systems. The optic response of the W/Si system was simulated based on the approximations from the theory of the effective medium including the interfacial layer in the model. In the analysis use was made of the dielectric functions of the W and the Si films determined separately.
Computer-aided mode diagnostics and parameters optimization of a picosecond laser setup based on a modified Sagnak interferometer
Dmitry N. Boldovskii, Eugene A. Tikhonov
The method of computer aided diagnostics of the picosecond laser set-up is realized and offered for testing of ultra short pulses laser. The method is based on registration of correlation function series at one pass of the optical delay line of the correlator with pulses selection by energy. Method allow to obtain laser pulses statistical distribution by duration and energy. Realization of the offered method provided with the information on parameters of lasing and with the appropriate ways of parameter optimization.
Use of photodepolarization spectra for diagnostics and characterization of alternating current thin-film electroluminescent (ACTFEL) devices
Nataliya A. Vlasenko, A. I. Beletskii, Z. L. Denisova, et al.
New non-destructive method of diagnostics and characterization of ACTFEL devices based on analysis of experimental and calculated photodepolarization spectra is proposed. This method gives an important information concerning the signa nd spatial distribution of polarization charge which influence significantly on characteristics of ACTFEL devices. The methodology and various variants of the method are considered. The simulation of PDP spectra is provided. Capabilities of the method are illustrated by the PDP spectra of ZnS:Mn and SrS:Ce devices fabricated by various techniques.
Photoacoustic techniques for determination of thresholds of failure during laser processing of substrate materials for integrated electronics
Sergiy M. Baschenko, Ivan V. Blonskij, Viacheslav M. Puzikov, et al.
Possibility of application of the photoacoustic methods for determination of threshold of failure of plates caused by power light pulses (up to 300 MW/mm2) of the excimer XeCl* laser is demonstrated. The original system on the basis of the XeCl* laser for a high-precision processing of sapphire plates and other construction materials is developed.
Radiation-stable infrared optical components
Nicolai D. Savchenko, T. N. Shchurova, A. Kondrat, et al.
High-energy electron (E equals 6.5 MeV) irradiation effect ((Phi) equals 1016 cm-2) on the optical transmittance in the wavelength range from 0.4 micrometers to 25 micrometers for Ge, ZnSe, LiF, BaF2, KRS-5, Csl and chalcogenide glasses of IKS-type and on the absorption edge for thin films deposited from Ge-As-Se glasses has been studied. The method of the computer-aided search for the glass compositions with the maximum stability to the high- energy irradiation has been developed. The most stable compositions of the Ge-As-Se system have been found to be the ones closed to As2Se3Ge1 glass, being in the agreement with the experimental results. Experimental verification of the analysis by the testing of the both sides 5.25 micrometers antireflected BaF2 component with two- layer antireflective coating that comprises the high- refractive layer deposited from the selected radiation stable glass Ge16.7As33.3Se50 and the low- refractive layer of ZnS at the specified operating conditions: electron fluence (Phi) equals 4 X 1017 cm-2s-1, has shown the stability of its performances in the operation wavelength region.
Effects of structure microdefects on scintillation and photostimulated properties of CdWO4 crystals
V. G. Bondar', S. F. Burachas, Konstantin A. Katrunov, et al.
CdWO4(CWO) scintillator single crystals find broad applications as detectors of ionizing radiation in tomographic and introscopic devices. Scintillation characteristics of the crystals are strongly dependent upon growth conditions. In this paper the nature of the defects is studied, related to deviations from stoichiometry and presence of admixtures, for the crystals grow by the Chochralski method. Negative effects of admixtures (Fe, Cu, Bi, Ga ions) on the light yield and afterglow in CWO crystals were established. Photosensitivity of CWO crystals under UV-radiation was noted in the region of the fundamental absorption edge, causing the induced absorption ((alpha) up to 1.5 cm-1) and a decrease of the light yield (to 30%). The studies have shown that the induced absorption depends upon both admixtures and non- stoichiometry. Basing on the results, preparation conditions were optimized for large-sized (55 X 250 mm) CWO crystals, allowing to obtain scintillation characteristics meeting the requirements for their use in radiation detectors for tomography and introscopy.
Measurement and spectrometry of fluxes of charged particles using a scintillator-photodiode-preamplifier (S-PD-PA) and new types of scintillators based on semiconductor AIIBVI compounds
Vladimir D. Ryzhikov, Vyacheslav V. Chernikov, Leonid P. Gal'chinetsky, et al.
Scintillators based on AIIBVI compounds, having relative small effective atomic numbers, can be used for measurement and spectrometry of fluxes of light and heavy charged particles. In this paper we attempted to specify the possibilities and limitations of the development of new types of solid-state detectors of charged particles and corresponding instruments on the basis of CdS(Te) and ZnSe(Te) scintillator single crystals produced by STC RI of the Concern `Institute for Single Crystals'. Principal attention was paid to a promising system S-PD-PA, combined with modern computer facilities. For the best specimens of instruments, we obtained energy resolution for alpha- particles with E(alpha ) equals 5.15 MeV R(alpha ) equals 4- 5%, for electrons with Ee equals 0.624 MeV equals Re equals 11-12%, alpha to beta ratio (alpha) /(gamma) equals 1.0 +/- 0.1, beta to gamma ratio (beta) /(gamma) - more than 100. A possibility is discussed of a combined method of detection and spectrometry of electrons in the energy range of 0.015 - 3.0 MeV using a windowless silicon PIN-PD (0.01 - 3.0 MeV), as well as a scintillation detector comprising a scintillator and a PIN-PD (0.2 - 3.0 MeV).
Laser damage threshold and microfaultness of large KDP crystals
Vitaly I. Salo, V. F. Tkachenko, M. A. Rom, et al.
The faulty microstructure of KDP samples having different bulk laser damage threshold (4 X 1010 W/cm2 - 5.4 X 1011 W/cm2 was studied using the methods of the three-crystal x-ray diffraction and two-crystal topography on reflection. A correlation between the dispersion of the structure-sensitive parameters characterizing the microfaultness and the value of bulk laser threshold of samples cut off large KDP crystals was established.
Effect of impurities on the value of the bulk laser damage threshold of KDP single crystals
Vitaly I. Salo, Marina I. Kolybayeva, Viacheslav M. Puzikov, et al.
The paper is devoted to studying the influence of Cu, Si, Pb and Cr impurities (possessing no absorption bands at the wavelength of acting laser irradiation) on the value of bulk laser damage threshold and UV absorption in KDP single crystals. It is shown that for the investigated concentration range (1(DOT)10-5 - 1(DOT)10-2 mass%) laser damage threshold essentially decreases with raising the concentration of impurity ions in the crystal lattice. The maximal value of the said characteristic (approximately 40 J/cm2) is found to be achieved in the case when the concentration of impurities is not less than 1(DOT)10-5 mass%.
Optical and photoelectric- and gas-sensitive properties of porous silicon
Valentin A. Smyntyna, Yurij A. Vashpanov
The photoelectronic properties of samples of porous silicon received by method of anodic electrochemical etching of monocrystalline silicon in electrolytes on the base of hydrofluoric acid are investigated. Wide spectral photosensitivity from infra-red to ultraviolet of spectrum area on series of received structures is found out. The physical mechanism of photosensitivity is discussed. The electronic parameters of porous silicon samples under gas adsorption were investigated. It was opend that the ammonia adsorption changes electrical conductivity of porous silicon samples on constant and variable current of measurement. In microporous asymmetrical structures we observed electromotive force on contacts under ammonia adsorption. The physical mechanism of adsorption of ammonia is connected with interaction dipolar molecules ammonia with double electric layer on surface of porous silicon.
Optical inhomogeneity and defect formation in Mg-doped lithium niobate single crystals
N. I. Deryugina, K. Polgar, V. M. Gabu, et al.
We performed the complex investigation of optical inhomogeneity and defect formation processes in Mg-doped lithium niobate single crystals with different dopant concentrations including the over-threshold one (LMNO crystals). Using radiospectroscopic methods we have found the Mg impurity doping mechanism of LiNbO3 crystals on the microscopic level. It has allowed us to give the noncontradictory explanation of the optical inhomogeneity properties of LiNbO3:Mg single crystals on the macroscopic level. The recommendation on the effective utilization of LiNbO3:Mg crystals in laser beam control equipment was proposed.