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The specific features of the formation of concentration inhomogeneities in crystals grown by the Czochralski method (GaSb:Te, Ge:Ga) and by the Bridgman method (Y3Al5O12:Nd, ZnGeP2, GaSb:Te, Ge:Ga) are analyzed. Digital processing of growth striation (GS) images showed the presence of strict periodicity in the GS distribution along the boule length for the Czochralski-grown crystals (rotational GSs) and the absence of systematic GS distribution for the crystals grown by the Bridgman method. Possible reasons for the observed regularities of variation in crystal composition are discussed.

Vertical through Si(Ga) p channels are created at 1450 K in c-Si(111) plates by thermomigration of local gallium zones. To this end, a technique is proposed and implemented for the formation of local zones consisting in the filling of linear grooves with a of width 60−100 μm and depth of 30−50 μm etched in the silicon plate with a fine-grained Ga powder. It is shown that a high yield of acceptable zones occurs with powder grains with a size of 5 μm and at ∼284 K. The obtained thermomigration Si(Ga) p channels are studied by the X-ray methods of double-crystal diffraction reflection curves and projection topography. The structural perfection of gallium p channels is characterized based on their comparison with features of the structure of thermomigration Si(Al) channels, obtained close to retrograde temperature 1380 K. It is shown that dislocation half-loops pinned at their ends at the boundaries of both thermomigration channels are a typical form of structural defects at their boundaries. The magnitudes of deformation of (2−5) × 10–5 and bending of 15″−30″ of the crystal planes close to the channel–matrix of the plate interface of the samples under study are determined. In the Vegard model, the concentration of aluminum and gallium atoms implanted into a crystal lattice of the silicon channels of the samples was CAl ∼ 1019 cm−3 and CGa ∼ 1.9 × 1019 cm−3, respectively.

A technique that allows one to form thick thermomigration silicon layers heavily doped with gallium for prospective power electronic devices is proposed. The dependences of the perfection of structure and the composition of the layers on the temperature of their formation were studied by the methods of X-ray topography, X-ray reflection curves, and secondary-ion mass spectrometry. It is established that the formed layers are single-crystal layers and do not contain misfit dislocations at the interface with the silicon substrate. It is shown that the concentration of gallium in the layers can be varied in the range of (1.6–4.8) × 1019 cm–3, which is higher than the concentration achieved in the case in which silicon is doped with aluminum.

Objective factors that allow the experiment on growing crystals of a Ge–Si–Sb solid solution on the Soyuz–Apollo spacecraft to take a special place among many experiments on growing single crystals aboard spacecrafts are analyzed. In the study of crystals grown on board a spacecraft, anomalous and unexpectedly high segregation of the solid solution components in the direction transverse to the direction of crystallization is found. An analysis of the obtained results allowed us, for the first time, to establish a causal relationship between anomalous segregation and microgravity features on board a spacecraft. Determining the physical nature of anomalous segregation have affected the direction of further research and give rise to an in-depth study of specific features of the new technological environment, the rapid development of numerical methods for studying heat and mass transfer processes in melts, and the expanding of the range of studied crystals and methods for studying them. A great contribution to the development of this area was made by Professor V.S. Zemskov.

The formation of the block structure and residual stresses in sapphire single-crystal tubes grown from the melt by the Stepanov method has been studied. The distribution of the difference in the residual stress tensor components (σφ–σr) in a thick-walled [0001] sapphire tube has been measured by the conoscopy method. It has been shown that circumferential tensile σφ and compressive stresses act on the outer and inner tube surfaces, respectively. The maximum stress is ∼20 MPa. It has been demonstrated that the development of the block structure begins from the outer tube surface; as the crystal length increases during growth, blocks propagate over the entire cross section.

The formation of blocks in shaped sapphire rods of two crystallographic orientations has been investigated. It is shown that, when growth occurs in the direction of the optical c axis, blocks are formed with a higher probability than in the case of growth in the a direction. A model of formation of blocks in rods of different orientations is proposed. The distribution of residual stresses over sapphire rod cross sections is measured by conoscopy. It is found that stresses increase from the middle of a rod to its periphery and reach 20 MPa.

X-ray topography and high-resolution diffractometry methods are used for testing GaAs wafers from different manufacturers, which are used as substrates for epitaxial growth in construction of power semiconductor devices. Typical features of such wafers are a distorted surface layer, bent, and growth dislocations with two types of distribution with a density of (1–2) × 104 cm−2. The best and worse substrates are determined from the finishing of the working surface, and the optimal combination of X-ray methods for estimating the quality of finishing of the working surface of the crystals with a high level of X-ray absorption is established.

Problems concerning the technology of growing highly homogeneous semiconductor crystals are discussed. The dependence between the inhomogeneity of GaSb:Te substrates and the efficiency of thermophotovoltaic converters (TPVCs) fabricated on their base via the diffusion technique is examined. The macro- and microhomogeneities of grown crystals can be substantially increased on account of the theoretically substantiated and experimentally implemented approximation to diffusive mass transfer conditions in the melt. The characteristics of TPVCs on substrates made of crystals with the most homogeneous properties exceed the analogous characteristics of other samples.

In this paper, which is dedicated to the 100th anniversary of the discovery of X-ray diffraction (which occurs in 2012), the role and significance of X-ray diffraction topography for materials science are described. The basic principles, methods, and history of the development of X-ray topography (XRT) are briefly stated. A wide experience of practical application of XRT to study the mechanisms of formation of real structure in bulk single crystals and thin films is summarized. Examples of the application of topography methods for investigating and optimizing the production technology of a variety of practically important materials and microelectronic devices are presented.

The results of comparative studies concerned with the formation of impurity heterogeneity in GaSb:Te crystals grown at the POLIZON facility by the Bridgman method under space and ground conditions are presented. Crystallization is carried out in the same temperature-time modes of the heaters: on board the Foton-M 3 spacecraft in space and by the vertical Bridgman method under conditions of weakened thermogravitational convection on Earth. In both cases, Marangoni convection is eliminated, and the effect of vibration microaccelerations on the ampoule that contains the melt is minimized. The microuniformity of the dopant distribution in the crystal areas that are recrystallized by the Bridgman method is higher than that in the seed grown by the Czochralski method. Microuniformity is higher under space conditions than under ground conditions with weakened thermogravitational convection. Spectral Fourier analysis of the spreading resistance distribution Rs reveals the characteristic periods of heat and mass transfer processes in the melts under ground and space conditions.

The history of the growth of semiconductor crystals aboard space vehicles and their subsequent investigation has been described shortly. It has been shown using Ge(Ga), GaSb(Si), and GaSb(Te) crystals as an example that the formation of segregation growth striations can be avoided during their recrystallization by the vertical Bridgman method in conditions of physical simulation of microgravity on the Earth, mainly due to the essential weakening of the thermal gravitation convection. By their structure and impurity distribution, they approach the crystals grown in space. The investigation of recrystallization of Te has made it possible to determine the role of the detachment effect characteristic of the microgravity conditions and the features of the microstructure of the samples that crystallize with a free surface. The analysis of the results obtained from experiments in space allows us to better understand the processes occurring during the crystallization of the melts and to improve the crystal growth in terrestrial conditions.

The possibilities of high-resolution X-ray section topography using the geometry of the interference bands to reveal features of the elastic fields of crystalline lattice defects are considered. The mechanisms of the diffraction of the X-ray wavefield on elastic lattice distortions are demonstrated using the example of dislocations. Microdefects in silicon are another most interesting subject. Section topography is in this case virtually the only method for revealing very weak deformations due to microdefects.

The ways in which a block structure is formed in shaped sapphire single crystals grown from melt by the Stepanov method are considered. The measured temperature distributions and results of a mathematical modeling of the heat exchange in the growth zones, as well as the calculated thermoelastic fields and measured residual stresses, are reported. The possibility of effectively controlling the thermal fields and growth of block-free crystals by choosing optimal screening is shown for single crystals in the form of tubes and basal-plane-faceted ribbons.

A study of deep levels in InGaAs/GaAs and GaAsSb/GaAs p0–i–n0 heterostructures with misfit dislocations and identification of the effective defects responsible for the significant (by up to a factor of 100) decrease in the relaxation time of nonequilibrium carriers in the base layers (and in the related reverse recovery time) of InGaAs/GaAs and GaAsSb/GaAs high-voltage power p-i-n diodes is reported. Experimental capacitance–voltage characteristics and deep-level transient spectroscopy spectra of p+–p0–i–n0–n+ homostructures based on undoped GaAs layers without misfit dislocations and InGaAs/GaAs and GaAsSb/GaAs heterostructures with a homogeneous network of misfit dislocations, all grown by liquid-phase epitaxy, are analyzed. Acceptor defects with deep levels HL2 and HL5 are identified in GaAs epitaxial p0 and n0 layers. Dislocation-related electron and hole deep traps designated as ED1 and HD3 are detected in InGaAs/GaAs and GaAsSb/GaAs heterostructures. The effective recombination centers in the hetero...

Si(As, P, B) and GaSb(Si) single crystals are used as examples to demonstrate the possibilities of methods of X-ray diffraction for the diagnostics (examination of a real structure) of highly doped semiconductor crystals. Prominence is given to characterizing the state of impurity: whether it is in a solid solution or at a certain stage of its decomposition. An optimum combination of X-ray diffraction methods is found to obtain the most complete information on the microsegregation and structural heterogeneity in crystals with low and high X-ray absorption. This combination is based on X-ray diffraction topography and X-ray diffractometry methods having an increased sensitivity to lattice strains.

The section Lang method of X-ray diffraction topography in combination with X-ray diffractometry based on the Borrmann effect was previously shown to be effective for detection of cluster formation during the growth process of highly doped Si-Cz single crystals. In the present work, the same techniques have been used to choose the best condition of technological heat treatment of boron-doped silicon from the view-point of formation of microdefects. The concentration and average size of dislocation loops have been calculated for two conditions of standard heat treatment from the analysis of diffusion scattering. The distribution of dislocation loops along the growth axis and crystal diameter has been determined as well.

Concentration and structural inhomogeneities in highly doped GaSb(Si) single crystals grown under various conditions of heat and mass transfer are studied by methods of X-ray topography, high-resolution X-ray diffractometry, and digital image processing. It is established that the inhomogeneity of crystals is determined by specific features of impurity microsegregation during growth under conditions of nonstationary convection in a melt and by peculiarities of the dislocation structure of crystals. The processes related to the initial stage of the decay of the Si supersaturated solid solution in GaSb contribute considerably to the inhomogeneity of crystals on the micro- and macrolevels.

The structure of basal-plane-faceted sapphire ribbons with cross sections of 30 × 1.5 and 50 × 1.5 mm, grown by the Stepanov method, has been investigated using X-ray diffraction topography and selective etching. The model of block formation in such ribbons through interaction of dislocations of prismatic slip system is confirmed. The role of gas bubbles as stress concentrators and dislocation sources is established. It is shown that the dislocations of basal-slip system are involved in the development the low-angle boundaries and block formation.

The possibility of controlling the heat-and-mass transfer processes to achieve steady-state conditions of gallium antimonide crystallization by the vertical Bridgman method with a upper heat supply was studied using the “Polizon” setup. Steady-state conditions near the crystallization front are achieved due to elimination of the Marangoni convection, growth axis orientation along the gravity vector, minimization and optimization of the radial and axial temperature gradients, respectively, and crystallization during steady motion of the temperature field along a cell with a sample without its mechanical motion with respect to heaters. The experimental results were compared with numerical calculations of the heat-and-mass transfer processes and crystallization parameters, including those for microgravity conditions.

Microsegregation and structural inhomogeneities in highly doped GaSb(Si) and InAs(Ga) single crystals grown under various heat and mass transfer conditions were analyzed using X-ray topography, high-resolution X-ray diffractometry, digital image processing and spectral analysis of signals. It was shown that a decrease in the convective flow intensity during crystal growth by the vertical Bridgman method with axisymmetric upper heat supply eliminates microsegregation growth striations and improves homogeneity of crystals on a micro-scale in comparison with the Czochralski method. Some specific features in X-ray topography images of growth striations caused by a high silicon concentration and dopant state deviation from an ideal substation solid solution were revealed in GaSb(Si). It is established that elastic stresses arising at large compositional variations in growth striations can relax by means of misfit dislocations formation. The magnitude of compositional fluctuations in InAs(Ga) was quantitatively estimated using conditions of misfit dislocation formation in such layered-inhomogeneous crystals.

The defect structure of basal-plane-faceted sapphire ribbons 10, 30, and 50 mm wide is investigated. It is shown that the high density of blocks in these crystals is associated with the specific features of the plastic deformation of the crystals with this orientation during crystal growth. In the basal-plane-faceted ribbons, the plastic deformation begins with the slip in the prismatic system. Dislocations of this system form characteristic low-angle boundaries, which then transform into block boundaries. It is revealed that the slip in the easiest basal system, which is characteristic of ribbons with all other orientations, is impossible because of the geometric constraints. Block-free basal-plane-faceted ribbons 50 mm wide are produced by decreasing thermal stresses in growing crystals.

Structural features of GaSb(Si) single crystals grown under various heat and mass transfer conditions were studied by x-ray topography and by double- and triple-crystal diffractometry. It was shown that a decrease in the convective flow intensity during crystal growth by the vertical Bridgman method with axisymmetric upper heat supply in comparison with the Czochralski method eliminates growth striations (caused by microsegregation) and improves the uniformity of electrical parameters of materials. According to triple-crystal x-ray diffractometry data, the increased density of structural defects observed in some crystal regions causes significant lattice distortions, which makes an additional contribution to crystal inhomogeneity. Some specific features in x-ray topography images of growth striations, caused by a high silicon concentration and a dopant state deviation from an ideal substitutional solid solution, were revealed.

Results of ground-based experiments on crystallization of gallium antimonide on the POLIZON facility carried out within the framework of space experiment preparation aboard FOTON satellite are submitted. Technical and technological opportunities of suppression of disturbing factors for improvement of quality of grown crystals in space are substantiated. Features of formation of concentration and structure inhomogeneities in GaSb:Si crystals grown under non-stationary and stationary convection conditions are investigated. Experimental data about structure and dopant distribution inhomogeneities are discussed taking into account results of numerical researches of GaSb:Si crystallization. Also earlier received results of modeling of GaSb:Te crystallization under close temperature conditions are used. Correlation between computational and experimental data is shown. The data on intensity of flows close to crystallization front are received at which non-stationary or stationary conditions of crystallization are realized. The forecast for space conditions is made. The influence of a rotating magnetic field on convection in melt for application in space experiment projected is investigated.

Concentration microinhomogeneities in crystals were characterized using x-ray topography, digital image processing, and spectral analysis of signals. Based on the features in lattice strains in such layered inhomogeneous crystals, methods for optimizing the conditions of x-ray topography detection of growth striations were proposed to obtain quantitative information on the composition fluctuation amplitude and spatial characteristics.

It is shown that effective diagnostics of strongly doped Czochralski-grown silicon single crystals in the initial (as-grown) state is provided by methods based on the interference phenomena of dynamic x-ray diffraction: the Lang section topography and the Borrmann effect diffractometry. The conditions of a test for the structural perfection of as-grown crystals, based on the observation of interference bands on the section topographs, are refined.

Peculiarities of the real structure of Ge(Ga) single crystals grown under external mechanical perturbations of the crystallization process simulating actual microgravity environment aboard spacecrafts were investigated by X-ray topography and diffractometry methods, etching analysis and spreading resistance measurements. The applied perturbations included vibrations and variations of growth facility orientation with respect to the direction of gravity force. It has been shown that microinhomogeneity of the crystals grown is defined not only by formation of dopant growth striations at peculiar vibrational perturbations of a melt, but also by specific features of dislocation structure of crystals related with the formation of small angle boundaries, slip bands and other inhomogeneities in dislocation distribution. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

An experimentally verified model of a block structure generation in basal-faceted sapphire ribbons is developed from three-dimensional thermoelastic stress computations and X-ray measurements. The reason for the typical block generation in the thin-faceted sapphire ribbons is a switching between the basal and the prismatic slip systems. The prism slip system acts only if the basal facet deviates from the ribbon side surface less than ∼3°. Dislocations generated by the prismatic slip are only able to create blocks typical for the basal-faceted ribbon. Since some faceted ribbon width, estimated as 5 mm, the prismatic slip does not act and the typical blocks do not generate. From computations supported by X-ray measurements a local increase of the thermoelastic stresses around bubbles was estimated as a factor of 2–2.5.

An analysis of possible reasons of block formation in sapphire ribbons with a basal faceted surface is performed. Capillary problem, radiative heat transport, dislocation structure and thermoelastic stresses are considered. It is shown that blocks arise as a result of dislocation generation in a prism slip under the action of thermal stresses. Basal faceted ribbons free of blocks are demonstrated.

The deformation behavior of a macroporous silicon wafer subjected to high-temperature oxidation has been studied, and the basic parameters describing the sample bending and subsequent stress relaxation when oxide is removed are determined. X-ray diffractometry and topography were used to determine the sample bending radius and lattice parameters, and to reveal the areas of dislocation generation. The strain of a silicon lattice in oxidized macroporous Si is about 10−4, and it decreases by an order of magnitude after oxide dissolution. The plastic part of the strain is accompanied by the generation of dislocations in the most strained regions of a structure, i.e., at the interfaces between the porous layer and substrate in the vertical direction and between the central porous region and the pore-free edge in the horizontal plane. The dislocation density is ∼104 cm−2.

The effect of gravity (from micro-to a rather high gravity, 5g0) acting during tellurium crystallization on the concentration of neutral (ND) and electrically active (NAD) acceptor-type structural defects in samples grown both under complete remelting of the starting ingot and under directed seed recrystallization of an ingot was studied. The concentrations NAD and ND and their distribution over the sample length were derived from the electrical characteristics (conductivity and the Hall effect) measured along the ingots in the temperature range 1.6–300 K. The contributions of various mechanisms to hole scattering were found from an analysis of the temperature behavior of the mobility. The results obtained were compared with the characteristics of samples grown following a similar program under normal conditions. The presence of NAD defects is characteristic of the initial crystallization stage of all samples. NAD is substantially lower (NAD ∼ 1015 cm−3) than ND ∼ 1018 cm−3 and decreases exponentially in the course of sample crystallization. Complete remelting under microgravity revealed indications of strong supercooling and spontaneous crystallization, as well as spatial oscillations of the electrical resistivity over the sample length caused by ND modulation. These observations are related to the specific features of the melting and crystallization in zero gravity, namely, the melt breaking away from the wall of the ampoule and the increasing role of Marangoni convection.

The paper considers the physical basis for the technique of controllable defect formation at heterointerfaces and in the bulk of epitaxial GaAs layers in the process of isovalent doping. Results of studying crystal defects and their rearrangement depending on the isovalent doping modes in the process of epitaxial growth are presented. The main aspects of the defect influence on the charge carrier lifetime as well as on the diode structure blocking voltage are analyzed. Particular cases of the developed technique application for controllable defect formation in fabricating such GaAs-based devices as Hyper Fast Recovery Epitaxial Diodes and Drift Step Recovery Diodes are considered.

The changes in the real structure of CdTe monocrystals caused by the thermal action of a high-power laser pulse (1.6–1.97 J/cm2) were studied by high-resolution x-ray topography and diffractometry methods. It was shown that, under our experimental conditions, in a thin surface layer within the crystal region exposed to the radiation, a dislocation cell structure with an increased dislocation density and with considerable micromisorientations, in comparison with the crystal region unexposed to the radiation, was formed. The characteristics of this modified crystal region were determined, and the thickness of the layer with the changed structure was estimated.

The crystal lattice structure of a microchannel silicon and variation of this structure in the course of thermal oxidation were studied by X-ray diffraction and topography techniques.

It is demonstrated that X-ray topography can be used for imaging the boundary between a microchannel silicon layer and a substrate, evaluating the quality of this interface, determining the channel depth, and revealing mechanical stresses. This technique can be used for nondestructive monitoring of the structure of a microchannel layer at a spatial resolution of ≥5 μm.

Real structure modification of CdTe single crystals exposed to pulsed radiation of ruby and Nd: YAG lasers is investigated using X-ray diffraction topography in the reflection configuration. The changes are mostly due to effects of heat in a thin surface layer. Depending on the incident laser energy, the following significant changes in the real structure of the crystal surface layer are observed: (1) integral improvement of the surface structure due to microstress relaxation; (2) the formation, development, and degradation of an ordered twin structure in the process of recrystallization; and (3) the formation of a fine-mesh dislocation structure. All these changes barely affect the bulk of the crystal. Mechanisms of the modifications are discussed, along with possibilities for their monitoring and control.

Three experiments on the tellurium recrystallization by a modified Bridgman method were performed under microgravity conditions on board the Mir orbital space laboratory using a ChSK-1 Kristallizator furnace. The physical properties of samples were studied, including the final crystal structure, the distribution of impurities and defects, and the charge carrier concentration and mobility. The results were compared to the analogous parameters of crystals remelted using the same method under the normal gravity conditions. It is established that the samples recrystallized in a close volume under the on-board microgravity conditions “break off” from the container walls and touch the walls only in a few points. This circumstance gives rise to special effects, such as the growth of crystals with a free surface and deep supercooling. Study of the distribution of electrically active impurities over the length of ingots shows evidence of the presence of thermocapillary convective flows in the melt under the microgravity conditions. The flows tend to increase upon separation of the melt from the container walls. The contributions due to impurities and electrically active structural defects to the charge carrier distribution are taken into account. The single-crystal sample obtained upon the partial recrystallization of tellurium in a close container volume under the on-board microgravity conditions exhibits the electrical characteristics comparable to those of a crystal grown by the Czochralski technique under the normal gravity conditions.

The Gd3+ EPR spectroscopy, radio-frequency (100 Hz — 1 MHz) diaelectric dispersion and X-ray diffraction studies of Cd2Nb2O pyrochlore over the temperature range of 80 K-300 K are presented and discussed from the viewpoint of structure instability and structure imperfection of the system.

Raman scattering, dielectric and optical studies of ferroic states in Cd2Nb2O7 pyrochlore within 77–205 K are presented and discussed. Coexistence of ferroic states of different nature and of a relaxor state in the ferroelectric phase of the compound is ascribed to weak bonding between two networks, (CdO8)n- and (NbO6)n-, in the pyrochlore structure.

Back-reflection x-ray diffraction topography is used the measure the real structure of the surface layer of CdTe single crystals. It is found that the structural changes depend mainly on the laser power, on the presence of a doping impurity, and on the orientation and profile of the sample surface. Three distinct and conspicuous phenomena are discussed: overall improvement of the real structure of the surface layer, the periodic relief of the crystal surface, and twin mosaic structure.

X-ray back-reflection topography with TV and photoplates recording as well as X-ray analysis technique have been applied to a number of sapphire single crystals shaped as 90° angles and tubes. It was done to study the formation and evolution of dislocation and mosaic structure in the shaped crystals with complicated cross-section. It has been shown that the real-structure formation in the origin part of the all shaped crystals, corresponding to its seeding and growing up to the steady-state dimensions has a principal significance for the next growth stages. The rotation of tube crystal orientation around its growth direction was first discovered and measured. The curl of tube crystals is discussed as one of the essential mechanisms of mosaic structure development and as some reaction of tube crystal to growth conditions.

Calorimetric and dielectric studies of nominally ‘pure’ Cd2Nb2O7 single crystals for a few thermal scanning rates in the temperature region 100–300 K are presented. The thermal hysteresis near the second-order phase transitions (PT) at Ts=205 K and Tc=196 K is due to ‘overheated’ ferroelectric state and is found to decrease with decrease a scanning rate. At room temperature, the X-ray diffraction topographic analysis shows an existence of a spatial cellular-like dislocation superstructure, with the cells being of a few microns. Below Tc, the relatively slow time-dependent processes are due to clamping the microscopic and tiny-scale domains by the microscopic dislocation superlattice and impurities. The processes developing on a long-time scale are ascribed to quasi-nonergodicity of the system long before a glassy state appears (below Tg ≈20 K).

Features of the X-ray topography (XRT) images of edge dislocations perpendicular to the (0001) surface of a 6H-SiC single crystal are described. The contrast of topographs obtained in the regime of anomalous X-ray transmission is compared to the contrast of images obtained using section X-ray topography in the transmission geometry.

Differential thermal analysis (DTA) and frequency-dependent complex dielectric constant studies of Cd2Nb2O7 were performed in the temperature region 77–300 K. Phase transitions at Ts, Tc and Tinc are found to be of a mixed order-disorder and displacive character. In the ferroelectric phase two distinct dielectric dispersions, characteristic for domain walls motion, are revealed. Below 150 K, dispersion developed at the low-frequency side is well fitted by the Cole-Cole formula with the anomalous temperature-dependent dispersion parameter h.

Physical basis of using the controlled defect formation in InGaAs heteroepitaxial layers to vary the carrier lifetime is considered. It is shown that the lifetime of nonequilibrium carriers in the base layers of a diode can be controllably varied from several to hundreds of nanoseconds. The results obtained in a study of (i) structural defects and their rearrangement related to the lattice mismatch between the heteroepitaxial InGaAs layer and the GaAs substrate and (ii) influence exerted by these defects on the carrier lifetime and on the voltage blocked by diode structures are reported. Dynamic switching characteristics of high-speed power heteroepitaxial diodes at different temperatures are presented.

Using the methods of X-ray topography and double-crystal diffractometry, investigations have been carried out concerning the formation of the real structure of epitaxial systems in the region of small mismatches ( Delta a/a

Silicon structures with vertical insulating walls were prepared for multielement devices with high element packing density requiring deep pockets in silicon single crystals. The technology is based on the anisotropic etching of (110)-oriented silicon crystals and filling the etch grooves with an organosilicon polymer based suspension.

X-ray topography and diffractometry are used to study the crystal structure of cadmium pyroniobate Cd2Nb2O7 at room temperature. Structural quality parameters were determined for crystals grown with different degrees of impurity doping. The nature of the crystal lattice damage is analyzed as a function of the type and concentration of impurities.

An analysis of the thermally induced domain behavior in Cd2Nb2O7 under cooling and heating in the dark has revealed that below Tc the coexistence of ferroelectric-ferroelastic domains of different types is accompanied by irreversible changes in the domains of the previous phase (Tc