Czochralski crystal growth method is discussed. Crystals of polycomponent oxides of pseudoperovskite structure are grown using convex interface, low gradient of temperature, and low growth and rotation rates. The knowledge of the crystal structure, morphology of crystals, and the attachment energy of faces allows us to design the crystal growth process. The change of color in ABCO₄ type crystal is related to oxygen point defects. The selected crystals are discussed as substrate crystals for high Tc superconductor thin layers.

Islanding and misfit relaxation are obstacles for MBE growth of high quality strained heteroepitaxial layers of lattice-mismatched materials. The growth mode in MBE, and thus the relaxation mechanism of such materials, is determined by balance between free energies of the substrate surface, the epilayer surface, and the interface. In order to reduce epilayer surface and interface free energies in comparison to substrate surface free energy, and thus suppress the process of island formation, use of segregating surface-active species (surfactants) during the MBE growth was proposed already in 1989. The pioneering work of Copel et al. on this subject has been followed by many experimental and theoretical works by other authors. The fundamentals of strained-layer MBE, as well as the most important physical arguments for using surfactants in MBE, are presented and discussed in the first part of this paper. The second part presents experimental examples of advantages resulting from using surfactants and, so called, virtual surfactants in MBE growth of strained heteroepitaxial structures of IV- IV and III-V semiconducting compounds.

Some difficulties in the melt-growth of II-VI compounds are clarified within a comparison between the properties of some II-VI and III-V compounds. Some specificities of the phase diagrams of both families of compounds, liquidus shape, width of the homogeneity range, existence of phase transitions in the solid state, and properties in solid, liquid and gaseous states, are related to the different characteristics of the compounds, and mainly to their chemical bond. Contamination from the environment is also shown to occur at high temperature, as illustrated in the CdTe case. The consequences of these factors on the crystal growth are analyzed, making attractive the use of low temperature growth. Solution and vapor growth are shown to present some limitations. Solid state recrystallization is presented as an attractive alternative and illustrated in the ZnSe case, for which very pure and perfect crystals are obtained, as assessed from photoluminescence and x-ray diffraction measurements.

The characteristics of different crystal growth techniques which are successfully used for the fabrication of epitaxial layers of CdTe, ZnTe, CdSe and ZnSe are compared. These techniques can be divided into two groups: first, the hot-wall-epitaxy and the hot-wall-beam-epitaxy working close to thermodynamic equilibrium, and second the atomic-layer epitaxy and the self-limiting monolayer epitaxy, which take some advantage to operate far away from thermodynamic equilibrium. With both groups of techniques epilayers and layered structures of high quality could be grown.

In this paper, the influence of the inductor design on the heat distribution in the growing floating zone silicon crystal is shown. Especially for the inductor profile and the slot width qualitative and quantitative results are given.

Nonlinear optics is a vast field requiring materials with different performance features. Rapidly developing world communication, demand for UV, blue or green light sources for computers, photolithography, color displays, etc. need novel more and more excellent nonlinear (NLO) and electro-optic (EO) materials. Many organic and inorganic crystals are presently known as the materials which can be used for these kinds of applications. Selected inorganic NLO and EO crystals used in practice are discussed and Chochralski growth of (beta) -BaB₂O₄ (BBO) crystals is presented.

Single crystals of La₃Ga₅SiO₁₄ were grown from the melt using the Czochralski technique. The mechanism of formation of most peculiar defects in La₃Ga₅SiO₁₄ crystals was studied and the possibility of their suppression by an essential modification of the growth assembly discussed. The piezoelectric behavior of the grown crystals at high temperatures was investigated.

LiYF₄ (YLF) is a very promising host material for lasers. Investigation of the spectroscopic and physical properties of YLF:Nd has suggested that this material may be a better candidate than Nd:YAG for generating short pulses with high peak power. This is a distinct advantage for many applications. Stimulated emission is attained at 1053 nm and 1047 nm. Also upconservation laser action in YLF and YLF:Er crystals is reported. More recently YLF doped with rare-earth elements has gained some attention. Pulsed room-temperature laser action at 2.06 micrometer has been achieved using YLF:Ho sensitized with Er and Tm. Using YLF:Pr blue light emission at 479 nm at room temperature was observed. Growth experiments of YLF:Nd crystals were carried by the Bridgman method. A vacuum furnace with cylindrical molybdenum heater and graphite crucible have been used. The temperature gradient of 25 degrees Celsius/cm has been achieved by using a stainless steel liner in the lower part of the furnace. The growth was performed in a nitrogen atmosphere. First crystals of YLF:Nd have been obtained.

Single crystals of LiNbO₃:Er³⁺, LiNbO₃:Tm³⁺, LiNbO₃:Er³⁺ + Tm³⁺ and LiNbO₃:Er³⁺ + Tm³⁺ + Mg²⁺ were grown by the Czochralski method starting from the congruently melting composition. Uniformly doped crystals were obtained at pulling rates 1 - 2 mm/h and rotation rates 5 - 20 rpm. The crystals were grown either in Y or in Z direction. The as-grown crystals were regular and free of macroscopic defects. The poling of crystals was carried out as a separate operation. Electrodiffusion was not observed during poling which was confirmed by x-ray microprobe analysis. The absorption spectra of Tm³⁺, Er³⁺ and Mg²⁺ doped LiNbO₃ single crystals were studied in spectral range 2000 - 28,000 cm^-1 at temperatures from 15 to 300 K. The interaction between Tm³⁺ and Er³⁺ ions resulting in changing of absorption spectra structure for particular terms related to Tm³⁺ and Er³⁺ ions has been observed.

Growth of Cr⁴⁺:YAG crystals as a relatively new laser material and their spectroscopic properties are presented. The possibilities of using these crystals for manufacturing of passive Q-switch modulators are pointed out.

SLAO crystals were grown from the melt by the Czochralski method. Undoped and doped with neodymium up to 5 at.% SLAO single crystals of [100] orientation were obtained. The optical transmission characteristics within the wavelength range of 190 - 7400 nm for undoped and Nd-doped crystals were measured. The results of ESR measurements in the temperature range 70 K to 4 K are also presented.

Nominally undoped and lightly Fe-doped semi-insulating InP can be prepared by thermal annealing under phosphorus vapor pressure. Semi-insulating undoped material obtained in this work has not indicated iron content. Thermal annealing process of InP:Fe with N_Fe <EQ 8 (DOT) 10¹⁶ cm^-3 improves its electrical parameters. The material has been characterized by: Hall effect and conductivity measurements, resistivity and Fe concentration distribution, photoluminescence measurements.

Studies were carried out on the crystallization of TiC_x for various values of x equals C/Ti from high temperature solutions of melted Ni and Al. Growth processes took place in Al₂O₃ crucibles in the temperature range 1500 - 1700 degrees Celsius. It was ascertained that during slow cooling of the melted solutions, TiC_x crystallized as primary crystals and on reaching the eutectic temperature for the quasi-binary system Ni-TiC_x, crystallization of eutectic Ni-TiC_x took place. Obtained crystals were of cubic or octahedral form, for Ni and Al solvents, respectively. They had metallic silver color and a maximum size of 1 mm.

Investigations of single crystal growth of potassium niobate (KNbO₃) have been reported. Top-seeded solution growth (TSSG) technique was used. Blue coloration and multi-domain structure were the main difficulties encountered during the experiments. Second harmonic generation was observed in as-grown crystals.

The basic technical data of the automatic facility designed for crystal growth from solution studies on board the space laboratory are presented. A brief description of the scientific program is included.

Experimental possibilities of the atomic force microscope as a tool for crystal growth from solution studies are presented. On the basis of our own research and literature data some common problems connected with the use of AFM for such purposes are discussed. Indication for future experiments are formulated.

Gel preparation technique is essential for crystallization in gel because the conditions in the crystallization environment depend on the type and properties of gel used for the experiment. Many substances introduced into the gelling mixture can change the time of gelation and the structure of the gel. In this work the time of gelation of tetramethoxysilan (TMS) gel was measured as a function of TMS and potassium dihydrogen phosphate (KDP) concentration in gelling mixture and temperature of gelation. Time of gelation increases with reducing TMS concentration and with augmentation of KDP concentration in gelling mixture. Decrease in temperature slows down the rate of gelling process.

Morphology of as-grown crystals of sodium chlorate obtained from pure solution has been interrelated with growth conditions. Crystals prepared at high cooling rates and supersaturations exhibit pure cubic {100} form. Crystal habit was modified by additional faces of {110} type at decreasing cooling rate and finally a new set of four crystallographically equivalent {111} faces was formed at a very low cooling rate. Surface features of all those types of the faces revealed the layer growth mechanism. Lang topography confirmed the presence of screw dislocations in all sectors under investigation, however, their density and structure is different for low and high cooling rates. Further investigations pointed out that four tetrahedral (111) faces present in the growth form are alternate to those observed in crystals grown from pure solution. X-ray analysis and liquid chromatography analysis of sulphur content confirmed the hypothesis that the impurity was built-in (111) growth sector. Therefore, further analysis of a possible surface site for impurity on these faces was performed and the hypothesis of the stability of these faces is discussed.

The solubility of fluoranthene in some halogen derivative organic solvents has been determined experimentally. These results have been correlated by using the classical equation for solid-liquid solubility and the obtained experimental activity coefficients have been compared to the values predicted on the basis of the regular solution theory. The best solubility correlation has been obtained with the extended regular solution theory. Thermodynamical characterization of the considered solutions is also given.

Influence of the growth solution volume on the values of the metastable zone width ((Delta) T_MET), the induction period ((tau) ), and the shape of the crystals has been determined experimentally. The growth solution of naphthalene-1,2-dichloroethane (1,2- dCHLE) was chosen as the model one. The errors due to the evaporation of the solvent were eliminated as the special procedure of measurements was used.

Data on the solubility of fluoranthene in some halogen derivatives solvents, nucleation parameters ((Delta) T_MET, (tau) ), and the relation between morphology of obtained crystals and their growth conditions (type of solutions, (sigma) _G, T_G) have been determined experimentally. Moreover, the enthalpy of dissolution ((Delta) H^S), enthalpy of mixing ((Delta) H^M), and activity coefficient ((gamma) _g^exp) of investigated solutions have been calculated and compared with the growth results.

The rate constant of the diffusion-controlled recombination of ions has been calculated for large (infinite) ensembles of nonseparable ion pairs. The computer codes have been constructed that simulate diffusion-controlled recombination of ions in model supersaturated solutions with different concentrations of ionic solutes and different dielectric constant of the solution. The simulation runs were performed for C equals 10^-4 M, 10^-3 M, 10^-2 M, 10^-1 M and 1 M and, independently, for a wide range of the dielectric constant, from epsilon equals 2 (nonpolar solvent) to epsilon equals 80 (aqueous solutions). The simulations yielded the ion survival probability as a function of time and allowed us to calculate the rate constant of the ion recombination as a function of the ion concentration. The calculated rates are compared with the theoretical Debye-Smoluchowski-type rate constant derived for isolated ion pairs and the Smoluchowski rate constant for neutral reactants. It appears, surprisingly, that the rate constant does not decrease with the increase of concentration (from the k_DS value to the Smoluchowski k value, as expected), even in the range of 1 M solutions. The rate constants, for a wide range of the dielectric permittivity, are slightly higher (by about 10 - 20%) than the k_DS rate constant and much higher, even by a factor of a hundred in nonpolar solutions, than the Smoluchowski rates.

The paper contains analysis of a well known Monte-Carlo crystal growth model taking into account surface diffusion. The assumptions being the basis of the model are analyzed, appraised, and modifications making them more physically acceptable are proposed. The numerical realization of surface diffusion is appraised as well, and means of its improvement are proposed. The results of the original and modified models are compared. The 'numerical roughening' effect was identified as a possible cause of roughening transition temperature uncertainty.

In most papers concerning theory of crystal growth the distance between turns of the growth spiral (step distance) is described by Cabrera and Levine approximation. However, other approximations of this distance are proposed in literature. The effect of the applied step distance approximations on the dependences of growth units concentration and crystal growth rate versus supersaturation are analyzed in this paper. The results of calculations show that the Cabrera and Levine approximation may be used for very low supersaturations only.

The Au(100) single crystal surface has been investigated at room temperature, in air, by scanning tunneling microscopy (STM). After sputter-annealing procedure the 1 by 1 surface partially reconstructs to form quasi-hexagonal domains. The reconstructed structure was found to be not twisted, with the interatomic distance of 2.9 plus or minus 0.2 angstrom. This result remains in good agreement with STM and surface x ray scattering (SXS) data performed in ultra high vacuum as well as in situ in the electrochemical cell.

A numerical technique has been used to solve the carrier transport equations for n⁺- p PbS, PbSe, and PbTe photodiode configurations. The model computes the spatial distribution of the electric field, electron and hole concentrations, and the generation- recombination mechanisms. Also the effect of doping profiles on the photodiode parameters (R_oA product, quantum efficiency) is analyzed. Results of calculations indicate the potential possibilities of constructing higher quality photodiodes. The R_oA product of experimentally measured PbS, PbSe, and PbTe photodiodes at low temperatures is controlled by Shockley-Read-Hall generation-recombination mechanism. In the range of higher temperatures, the influence of auger generation-recombination mechanism is also appreciable.

A review of the effect of the internal biaxial strain on the energy bands in thin film heterostructures composed of the cubic structure semiconductors is presented.

Strong magnetic field Hall coefficient and magnetoresistivity dependencies in PbTe/PbS semimetallic SLs with periods of 12.0 divided by 100.0 nm were observed. From the analysis of these dependencies by Monte-Carlo fitting procedure the band-offset (Delta) E_v equals 0.32 plus or minus 0.05 eV was obtained (T equals 77 K) and it was proved that these SLs are type II 'misaligned structures.' The band structure calculations of PbTe/PbS SLs in the envelope wave function approximation showed that in such SLs a semimetal-semiconductor transition should occur for layer thicknesses of approximately 6.0 nm.

This paper provides an introduction to some novel aspects of the transmission line matrix (TLM) numerical technique with particular reference to the modeling of processes in semiconductor materials and devices. It covers the relative merits of different forms of network representation of physical problems. Current progress with TLM algorithms for the Laplace and Poisson equations is reviewed.

Heat flow modeling by using the transmission line matrix method (TLM) was applied to simulate the pulsed heating which can be accomplished by absorption of radiation or during detonation of explosives. This work presents the results of calculations of time and spatial dependence of heat flow into a solid due to the pulsed radiation absorbed in the surface layer of the solid. The TLM method enables the accurate calculation of the rate of heat flow during and after the course of energy absorption in a thin surface layer. It permits us to determine temperature variation near the surface.

A simple procedure has been developed by which the doping profile of the semiconductor can be obtained right up to the surface. Contrary to the existing methods no restriction has been made on the shape of the profile.

On the basis of the reduced second-order self-consistent phonon approximation, based on the Green's functions method, the temperature and pressure variations of the dynamic and thermodynamic functions of strongly anharmonic crystals are computed and compared with experimental and other theoretical data. The system of self-consistent equations is solved for the generalized form of the Lennard-Jones (n,m) interatomic potential.

Kinetics of thermally stimulated conductivity (TSC) and thermoluminescence (TL) are considered using the classical trap model. Taking advantage of some recently derived analytical formulae we present new methods for determining trap parameters, especially the density of deep traps and activation energy, from thermally stimulated spectra. Approximate analytical solutions for TSC and TL in the form of a generalized 'initial rise' method are derived. It is shown that performing thermally stimulated experiments for different heating rates it is possible to determine some basic trap parameters by solving a simple non-linear equation. Relative error of the approximations is estimated numerically for various trap parameters. In most cases the error is less than 0.1% in the whole range of the spectrum.

Results of numerical simulation carried out for thermally stimulated conductivity (TSC) and thermoluminescence (TL) for various trap parameters and different correlation of traps and recombination centers are presented. Monte Carlo algorithm was generalized to include trap levels that are initially not fulfilled with carriers. The properties of thermally stimulated relaxation spectra, especially the dependence on initial filling ratio and recombination coefficient are discussed. The applicability of some classical methods developed for the evaluation of trap parameters from TSC and TL spectra is discussed. It was found that many TL and TSC spectra calculated for strong correlation between traps and recombination centers are of 'first-order' kinetics.

The basic differential equations describing thermally stimulated luminescence (TSL) and conductivity (TSC) in insulating crystal are numerically solved for different sets of recombination and trapping parameters without any additional assumptions. As a result different TSL and TSC characteristics are calculated for the case of temperature-dependent recombination and trapping coefficients. The results of calculations show that the assumption of quasi-equilibrium often used in the approximative description of the TSL and TSC phenomena is correct if the density of recombination centers in crystal is higher than 10¹⁴ cm^-3.

The experimental investigation results of different kinds of ionizing radiation's (gamma- quanta, electrons, protons, neutrons, neon ions) influence on the optical, electrophysical, structural properties of gadolinium gallium garnet (GGG) crystals are presented. Some crystal parameters have been obtained using the quantum-chemical calculations. With regard to this result the radiation damage concentrations have been calculated. For most likely defect configurations the defect level energies and optical transition probabilities have been determined by means of Green function method. The mechanisms of radiation-induced transformations and color center models are discussed.

Results of preliminary investigations of thermoluminescent response of CaSO₄Dy to ionizing radiation are reported. Very high sensitivity and good linearity of this luminofor are confirmed in the case of gamma irradiation. Neutron sensitivity of calcium sulphate due to internal conversion of ³²S to ³²P by fast neutrons was investigated as well, but it does not seem to be sensitive enough to be used in personal dosimetry.

The electroluminescent thin film cells based on ZnS:Mn were investigated. The ZnS:Mn and Al electrodes were produced by thermal evaporation and the Cu_xS layer was formed by a wet chemical process. The cells were excited by short rectangular voltage pulses of 10 microsecond(s) . The electroluminescence of the cells exhibited two exponential kinetic components with a long lifetime (tau) _s equals 333 microsecond(s) and a short lifetime (tau) _o equals 98 microsecond(s) . The maximum of the electroluminescence appeared after the end of the exciting pulse. Also nontypical behavior of the luminescence during the exciting pulse was observed. In order to explain the phenomena the energy transfer between monomolecular centers was assumed. It is shown that the relations based on the assumption fit well the experimental data for copper as the transferring and manganese as the emitting center.

This work deals with the study of luminescence properties of Zn_xMg_1-xSe layers prepared by different methods. Zn_xMg_1-xSe mixed crystal layers were obtained by: (a) thermal diffusion of Mg metal in the temperature range 1050 K - 1200 K into ZnSe single crystal grown by Bridgman method, and (b) epitaxial growth on (001) GaAs and (111) ZnTe substrates by MBE using elemental Zn, Se and Mg sources. The luminescence spectra of Zn_xMg_1-xSe layers grown on (001) GaAs and (111) ZnTe substrates are dominated by narrow blue and violet emission bands with maxima positioned at about 3.05 - 3.28 eV, 2.88 - 3.04 eV, and 2.81 - 2.705 eV.

Photoluminescence (PL), photoluminescence excitation (PLE), and decay times measurements on anodically etched boron-doped Si are presented. To explain our results we assume a model in which the multi-barrier structure is formed by Si crystal (quantum well) surrounded by Si quantum wires, oriented perpendicular to the sample surface with diameters in the range of 2 to 12 nm (barrier region). The visible photoluminescence originates from radiative recombination between discrete energy levels in quantum well.

This paper presents the results of an investigation of the temperature dependence of photoluminescence (PL) of electrochemically etched crystalline Si wafer. Luminescence spectra of porous silicon layers have been investigated as a function of temperature in the range between 35 K and 350 K. In general PL spectra consist of single broad emission bands with maxima positioned in the energy range from 1.75 eV to 1.95 eV at room temperature and 1.77 eV to 2.2 eV at T equals 40 K. A simple modeling of the PL band shape as a sum of Gaussian components indicates that four or more peaks exist within the response curve. Such analysis suggests that the luminescence in porous silicon arises from quantum confinement of the carriers in the silicon crystallites.

Values of the elastic constants C₁₁, C₁₂, and C₄₄ of the n-ZnSe single crystals with different free carrier concentration were studied using Brillouin light scattering method. It has been shown that the results obtained from Brillouin scattering study are in good agreement with the data obtained earlier from Raman scattering experiment. We also present the influence of the annealing procedure on the velocity of the elastic waves propagating in (110) and (111) planes for n-ZnSe single crystals. The large effect of the annealing procedure of the n-ZnSe single crystals in liquid zinc on their elastic properties has been discussed using theory proposed by Martin.

The characteristic changes in relative reflections intensity (without substantial change of their positions and without any additional reflexes from any new phases) on x-ray powder diffraction patterns from different doped A^IIB^VI compound crystals have been experimentally registered. On the basis of the powder diffraction data the changes in the lattice constants (increasing as well as decreasing) have been confirmed too. These changes have been tried to be connected with crystal structure under the assumption of statistical occupation of parts of positions chosen from positions possible to occupy in the lattice. The qualitative conformity of calculated relative intensity of x-ray reflections for the best matched models with obtained experimentally and also qualitative conformity of changes in lattice constants have been obtained for examined cases. Simultaneously the possibility of obtaining such conformity for other models (with dopants occupying other positions in lattice) have been excluded. It allows us to determine the position occupying by dopants and to estimate the relative contents of dopants.

Theoretical study of the ferroelastic domain structure of LiKSO₄ (LPS) in the ferroelastic phase below 190 K has been performed using Aizu theory. On the basis of this theory the determination of the state parameters and formulation of the spontaneous strain for all existing orientation states in this phase have been performed. It has been shown that the nature of the phase transition at 190 K, also the mechanical properties of LPS in the ferroelastic phase, can be affected by a ferroelastic domain structure.

Temperature study of Raman scattering in polycrystalline guanidinium iodide C(NH₂)₃I is presented. Temperature dependences of the Raman intensity and full width at half maximum (FWHM) for the two most temperature sensitive bands -- 510 cm^-1 and 1528 cm^-1 -- have been investigated. A significant decrease in intensities and an increase in FWHM of the modes studied are observed with an increase in temperature. Moreover, for both temperature dependences we have also observed very large hysteresis while the temperature was decreasing.

Experimental results of tunneling and Raman scattering of the high-T_c superconductor Bi₂Sr₂ CaCu₂ O₈ (BSCCO) are reported. Tunneling T-dependent conductance G(V,T) of evaporated Pb junctions on cleaved ab planes of the BSCCO (2:2:1:2) crystals is presented. We obtained a large energy gap, approximately (Delta) equals 26 meV at 4.2 K or 2(Delta) /k_BT_c equals 6.7. Temperature dependences of tunneling characteristics are in agreement with the well-known dependences for conventional superconductors. Raman spectra of the BSCCO single crystals were also performed in two different temperatures and excited with different laser lines. The typical Raman spectra of those kinds of crystals possess active sideband, which can be presumably attributed to the two- magnon scattering mechanism and high microscope superexchange constant J_exch was estimated.

Undoped and C-doped GaAs crystals, grown by the LP LEC and HP LEC techniques have been investigated. Carbon was incorporated into the melt during synthesis of monocrystallization in the range 6 multiplied by 10¹⁴ divided by 2 multiplied by 10¹⁶ cm^-3. Controlled carbon doping allows us to obtain SI GaAs crystals with high resistivity rho greater than 10⁷ (Omega) cm and high mobility mu greater than or equal to 5000 cm²/Vs.

Optical measurements of semi-insulating GaAs in spectral region 1400 - 500 cm^-1 are presented. The new absorption lines X5 (1201.8 cm^-1) and X4 (1317.5 cm^-1) are observed. It has been found that they are related to electrically active defects and are electronic transitions in nature. The coupling of the defect responsible for these lines with the lattice is stronger than CC model predicts. Our results seems to suggest that the lines are related to V_As defect.

Single crystals of SrLaGa₃O₇ undoped and doped with 5 and 10 at.% of neodymium were grown by the Czochralski technique. These crystals were investigated for their spectral properties. Absorption spectra in the range of 180 - 8000 nm were measured. Throughout the whole spectrum differential changes of the absorption were found. Optical transitions corresponding to this effect are indicated. The Nd-doped crystals were investigated for their lasing properties in the free-running generation.

Optical inhomogeneity is one of the most important parameters of oxide crystals widely used in optics and electronics. A computer-controlled imaging polarimeter has been applied for studying the optical inhomogeneities in several oxide crystals pulled by the Czochralski technique (Nd:YAG, Nd:SrLaGa₃O₇, LiNbO₃) or by the vertical Bridgman method (CaF₂, BaF₂). Three maps of the investigated sample-birefringence, the principal azimuth and transmission, are acquired within several seconds in a single measurement step. A quasiradial stress-induced birefringence distribution was observed in wafers cut out from the crystals pulled in the <111> direction and in Z-pulled LiNbO₃. The maximum residual birefringence was found at or very close to the perimeters of the wafers with the exception of YAGs where this maximum occurred close to the core region. The absolute value of birefringence in wafers cut out from the bottom parts of the crystals was typically larger than in adequate samples descending from the top parts. Such measurements enabled selection of the best crystal areas used then for production of electro- optic modulators (LiNbO₃) and lasers (YAG, SLGO).

Phenomena related to microstress at the SiOx/Si boundary in Czochralski grown silicon single crystals with the initial interstitial oxygen concentration up to 1.2 multiplied by 10¹⁸ cm^-3, subjected to annealing at up to 1620 K under hydrostatic pressure up to 1.35 GPa, were investigated by deep-level transient spectroscopy (DLTS), selective etching, Fourier transform infrared spectroscopy (FTIR), and x ray methods. Depending on treatment conditions the enhanced microstress at the SiOx/Si boundary, creation of additional nucleation centers, and change of precipitate critical radius can promote oxygen precipitation (retard OP dissolution) also causing creation of additional defects. Qualitative explanation of some observed phenomena is proposed.

In this paper the surfaces of {111}, {110}, and {100} homo-epitaxial layers of boron-doped diamond, grown by hot-filament assisted CVD, are examined by STM and optical microscopy. The STM results confirm the F- character of the {111} and {100} faces and the K-character of the {110} faces as was deduced from optical microscopy. However, only STM technique enables observation of individual nanometer scale steps, corrugations, and lattice imperfections arising during the diamond layers growth.

In the paper we present discussion of two methods of measurements and determination of spontaneous polarization and coercive field for materials showing dielectric hysteresis loop. The first method is based on the idea of Sawyer-Tower bridge (S-T), the second method is based on Diamand-Dreck-Pepinsky bridge. Based on available literature and previous experiences we constructed a computer measurement system for research over the shape of dielectric hysteresis loop. Using the above mentioned equipment we can measure spontaneous polarization (Ps), coercive field (Ec), and also shift field (Ep) in the case of dielectrics showing asymmetrical loop.

We compare several key infrared detector technologies versus operating temperature and background flux via hybrid FPA test at operating temperatures from 32.5 K to room temperature and photon backgrounds from mid-10⁵ to approximately equal to 10¹⁷ photons/cm²-sec. The detector materials include photovoltaic (PV) HgCdTe/Al₂O₃, PV HgCdTe/CdZnTe, photoconductive (PC) GaAs/AlGaAs quantum well infrared photodetector (QWIP) and PV InGaAs/InP; the device sizes range from 64 multiplied by 64 to 1024 multiplied by 1024.

Investigations of the performance of GaAs/AlGaAs quantum well infrared photoconductors (QWIPs) as compared to other types of semiconductor infrared detectors are presented. In comparative studies the HgCdTe photoconductors and photodiodes, Schottky barrier photoemissive detectors, and doped silicon detectors are considered. It is assumed that the performance of HgCdTe photodiodes is due to thermal generation governed by the auger mechanism in the base regions. Investigations of the fundamental physical limitations of HgCdTe photodiodes indicate better performance of this type of detector in comparison with QWIPs operated in the range 35 to 77 K. The operating temperature for HgCdTe detectors is higher than for other types of photon detectors. HgCdTe is characterized by high optical absorption coefficient and quantum efficiency and relatively low thermal generation rate compared to extrinsic detectors, silicide Schottky barriers and QWIPs. However, the cooling requirements for QWIPs with cutoff wavelengths below 10 micrometer are less stringent in comparison with extrinsic detectors and Schottky barrier devices.

P⁺-n long wavelength infrared radiation (LWIR) photodiodes were fabricated by arsenic diffusion into n-type HgCdTe bulk monocrystals. To improve the photodiode performance, a thickness of n-type base layer was limited. The photodiodes performance was determined from measurements of the current-voltage and spectral response characteristics. The generation-recombination current was found to be a dominant current around zero bias voltage at 77 K.

Medium- and long-wavelength infrared (MWIR and LWIR) Hg_1-xCd_xTe photodiodes (x equals 0.265 - 0.295, 0.205 - 0.220) for 3 - 5-micrometer and 8 - 12- micrometer wavelength spectral regions were fabricated by arsenic diffusion from the vapor source into the n-type HgCdTe bulk single crystals. The temperature dependence of current- voltage and capacity-voltage characteristics, and the photodiode speed response, were analyzed. For 3 - 5-micrometer photodiodes with the electron concentration 3 multiplied by 10¹⁵ cm^-3 in the base n-type layer, the typical resistance-area product at zero bias R_oA was about 10⁴ (Omega) cm² at 77 K. For 8 - 12 micrometer photodiodes with the same electron concentrations in the base region, the R_oA product values of 1 - 10 (Omega) cm² were obtained. The typical photoresponse speeds were in the range of 50 ns and 20 - 30 ns for 3 - 5-micrometer and 8 - 12-micrometer photodiodes, respectively. The dark current of fabricated photodiodes was tunneling limited at 77 K, and generation-recombination and diffusion limited at higher temperatures.

The performance of near-room temperature long-wavelength photovoltaic IR detectors has been analyzed. The ultimate performance of the devices is limited by the noise due to the statistical nature of thermal generation and recombination processes. Another practical limitation arises from the Johnson-Nyquist noise due to parasitic impedances and contribution of preamplifier noise. This is particularly significant for large area devices. Possible ways to overcome the difficulties are discussed.

Applications of thermoluminescence in ionizing radiation dosimetry as well as its nature have been discussed. Typical thermoluminescent materials, their advantages and disadvantages have been reported.

Basic principles of operating and main parameters of dc electrolyteless thin cells are presented. A short review of the most important results is reported. New experimental results and corresponding process mechanisms are presented. Large electric current density across the cell is explained by high velocity electroconvection. The structure of interface electrical double layer and charge emission in ultra thin cell are discussed.