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—Studies have been carried out and a technology has been developed for the formation of a separating mesa structure in fabrication of multi-junction solar cells based on the GaInP/GaInAs/Ge heterostructure. Methods for etching of the heterostructure layers have been studied: wet chemical etching in compositions based on HBr, K2Cr2O7, and H2O and the plasmachemical etching in a flow of the BCl3 working gas. A comparative analysis of the etching methods was made. Protective masks based on a photoresist layer and TiOx/SiO2 were developed. Multi-junction solar cells with low leakage current (less than 10–7 A at a voltage of 0.5–1 V) were fabricated.

We have studied the dynamics of air humidity in the interior of a concentrator photovoltaic (CPV) module equipped with air-drying device filled with moisture-absorbing material based on silica gel. A new design of the air-drying device was developed for preventing the deposition of condensate onto the surfaces of a Fresnel lens, solar cell, and CPV module. Under unfavorable ambient conditions (relative humidity up to 95%), this device allowed to reduce the inner humidity to 25–55% at cyclic temperature variation within 15–45°C and to increase the dew point deficit up to 10–25°C.

Methods for passivation and protection of p–n junctions at places of their emergence at the lateral surface of a mesa structure and for sealing-off of multijunction solar cells based on a GaInP/GaAs/Ge structure have been studied. Protective coatings based on silicon nitride and silicone layers were examined by analyzing dark current–voltage characteristics of the solar cells. The distribution of the electroluminescence was analyzed.

High-efficiency concentrator photovoltaic modules have been developed and fabricated. The modules include a lens panel based on 32 Fresnel lenses (12 × 12 cm each), 32 multi-junction solar cells with secondary concentrators in the form of phocons, and heat-removing electrically insulating boards based on an aluminum oxide ceramic placed on the backside aluminum base. Efficiency measurements of a 0.46-m2 module under a pulsed sunlight simulator (AM1.5D, 1000 W/m2) yielded a value of 32.3%. An efficiency of 33.9% was obtained for a subunit with an area of 144 cm2.

The power generation of the phtovoltaic installations depends on the concentration modules’ efficiency and the Sun tracking accuracy. We have developed a system for monitoring instant tracking accuracy based on a recorder and a projecting system of solar disk imaging.

The results of studies of characteristics of heat-removing electrical insulating plates of different designs based on heat-conducting AlN and Al2O3 ceramics and aluminum-oxide plates based on aluminum plates are presented. Thermophysical parameters of the heat-removing plates were assessed by measuring the temperature of p–n junctions of the photoelectric converters mounted on the plates with thermal load applied to them. It was found that the minimum overheating temperature of p–n junctions, 45°C, was observed at the supplied thermal power of 13 W, when the photoelectric converters were installed on the AlN ceramics. In photoelectric converters installed on the Al2O3 ceramics, the overheating of p–n junctions was 49°C, while it reached 70°C on the aluminum-oxide substrate.

Spectral characteristics of the Ga(In)As subcell of triple-junction GaInP/Ga(In)As/Ge solar cells have been experimentally and theoretically studied. It is established that the use of a wide-bandgap “window” layer with optimum thickness (100 nm for Ga0.51In0.49P, 110 nm for Al0.4Ga0.6As, and 115 nm for the Al0.8Ga0.2As) in Ga(In)As subcell allows the response photocurrent to be increased by about 0.5 mA/cm2; the change of material in the rear potential barrier of the GaInP subcell from Al0.53In0.47P to p+-Ga0.51In0.49P or AlGaAs allows the short-circuit current of Ga(In)As subcell to be additionally increased by about 0.8 mA/cm2; and the use of a wide-bandgap n++-Ga0.51In0.49P layer instead of n++-GaAs in the tunnel diode increases the photocurrent by about 1 mA/cm2.

Electrical supply sources based on photovoltaic converters and tritium radioluminescent lamps with blue and green glow are developed and fabricated. AlxGa1 –xAs/n-GaAs p–n heterostructures with various band-gap widths (Eg = 1.4–1.9 eV) and compositions of the active region (x = 0.1–0.35) are prepared by low-temperature liquid-phase epitaxy. The photovoltaic converter with an area of S = 0.12 cm2 upon irradiation by a green tritium lamp (wavelength λ = 550 nm) has the short-circuit current density 180 nA/cm2 and output electrical power >100 nW/cm2.

A multilayer system of ohmic contacts for GaAs/AlGaAs photovoltaic converters has been developed. A method of ohmic contact blackening is suggested with the aim of improving the coefficient of optical signal reflection from an Ag/Au/Ag multilayer contact. Owing to blackening, the reflection coefficient has been decreased more than tenfold.

Multi-junction solar cells based on III–V compounds are the most efficient converters of solar energy to electricity and are widely used in space solar arrays and terrestrial photovoltaic modules with sunlight concentrators. All modern high-efficiency III–V solar cells are based on the long-developed triple-junction III–V GaInP/GaInAs/Ge heterostructure and have an almost limiting efficiency for a given architecture — 30 and 41.6% for space and terrestrial concentrated radiations, respectively. Currently, an increase in efficiency is achieved by converting from the 3-junction to the more efficient 4-, 5-, and even 6-junction III–V architectures: growth technologies and methods of post-growth treatment of structures have been developed, new materials with optimal bandgaps have been designed, and crystallographic parameters have been improved. In this review, we consider recent achievements and prospects for the main directions of research and improvement of architectures, technologies, and materials used in laboratories to develop solar cells with the best conversion efficiency: 35.8% for space, 38.8% for terrestrial, and 46.1% for concentrated sunlight. It is supposed that by 2020, the efficiency will approach 40% for direct space radiation and 50% for concentrated terrestrial solar radiation. This review considers the architecture and technologies of solar cells with record-breaking efficiency for terrestrial and space applications. It should be noted that in terrestrial power plants, the use of III–V SCs is economically advantageous in systems with sunlight concentrators.

The postgrowth processing of mesa structures for multijunction solar cells based on GaInP/GaInAs/Ge heterostructure has been studied. Methods of wet chemical and electrochemical etching are considered, and a technology of forming a separation mesa structure is proposed that ensures improved surface quality and profile of the side wall of a mesa for heterostructures with various compositions of layers.

The results of the development of a radioisotope power supply source based on a semiconductor (AlxGa1 –xAs/GaAs) β-radiation energy converter and tritium as a radiation source are presented. The efficiency of this converter with a tritium saturated titanium disk, a green luminescent tritium lamp, or tritium gas as a radioisotope radiation source is compared. For a converter based on the Al0.35Ga0.65As/GaAs heterostructure in a capsule with tritium, efficiency η = 5.9% at a maximum specific output electrical power of 0.56 μW/cm2. Due to their long service life, such stand-alone and compact power supply sources can be used in space and subsea technologies, implantable cardiac pacemakers, biosensors, and portable equipment of high reliability.

The formation of antireflection coating on multijunction solar cells based on A3B5 semiconductor heterostructures has been studied at the stage of structure surface processing by methods of plasmachemical, wet chemical, and ion-beam etching. A technology of creating antireflection coatings based on TiOx/SiO2 layers is developed. The obtained coatings are characterized by improved adhesion to the surface of heterostructure and reduced reflection coefficient of multijunction solar cells.

Hybrid solar cells based on InGaP/Ga(In)As/Ge multijunction structures integrated into crystalline Si heat-removal base and provided with sunlight concentrator system based on linear Fresnel lenses and carboplastic mount structure have been developed and investigated. The hybrid solar cells with sunlight concentrators in the photovoltaic module provide a specific electric power of 390 W/m2 (AM0, 1367 W/m2) at a photoconverter unit specific weight reduced to 1.0 kg/m2. Improved photovoltaic characteristics and high radiation resistance allow using the proposed hybrid solar modules with sunlight concentrators in space solar batteries and autonomous power supply facilities.

Ohmic contacts of power AlGaAs/GaAs-based photovoltaic converters were studied, and a technique for their fabrication was developed. Effect of the doping level of the contact layer on the free-carrier density and the contact resistivity was examined. A technique for fabrication of 2- to 4-μm-thick ohmic contacts with electrochemical deposition of gold layers was studied. The effect of deposition modes on the surface morphology of ohmic contacts and their solidity and conductivity was revealed.

Spectral characteristics of the Ge subcell of triple-junction GaInP/GaAs/Ge solar cells have been simulated. It was shown that using a GaInP nucleation layer that creates a shallow diffusion p–n junction in Ge can raise the photogeneration current of the Ge subcell by ~4.5 mA/cm2 as compared with the value in the case of a GaAs nucleation layer. The optimal thickness of the GaInP layer (170–180 nm) makes it possible to additionally raise the photocurrent by ~1.5 mA/cm2. It was experimentally demonstrated that the photogenerated current of the Ge subcell of GaInP/GaAs/Ge solar cells increases by 3.9 mA/cm2 on replacing the GaAs nucleation layer with GaInP and there is an additional gain by 0.9 mA/cm2 on using the optimal thickness of the GaInP nucleation layer.

The influence exerted by the heat removal conditions on the extent of overheating of photovoltaic converters of high-power (>103 W/cm2) laser light has been studied. The temperature of the p–n junction of photovoltaic cells was measured by recording the instantaneous values of the open-circuit voltage generated by laser light. The effect of cooling in high-efficiency photovoltaic cells (efficiency = 55%) via removal of a substantial part of absorbed optical power by the photocurrent into the external load was demonstrated. It was shown that, at laser radiation power of 2.5 W, the overheating of a photocell with an area of 1.7 × 10–3 cm2 relative to the copper heatsink temperature is 48°C in the no-load conditions and 30°C in operation with the optimal load.

High-efficiency photovoltaic converters (PVCs) have been developed and fabricated by liquidphase epitaxy in the AlGaAs–GaAs system with laser light (λ = 850 nm) introduced through the edge surface in parallel to the plane of the p–n junction of the device structure. To raise the efficiency of light “capture” by the p–n junction, an AlxGa1–xAs waveguide layer is formed, in which the content of aluminum gradually varies from x = 0.55 to 0.15 so that the refractive index gradient is created in this layer and light beams are diverted toward the p–n junction. When a PVC (having no antireflection coating) is exposed to 0.1- to 0.2-W laser light, an efficiency of 41.5% is obtained. Depositing an antireflection coating on the edge surface of a PVC raises its efficiency to 55%.

This study is aimed at investigating the main photoelectric characteristics of three-cascade InGaP/InGaAs/Ge photoelectric converters in a broad temperature range (–197°C ≤ T ≤ +85°C). On account of analysis of photosensitivity spectra and optical current–voltage characteristics, such temperature dependences as the open-circuit voltage (V oc), filling factor of the current–voltage characteristic (FF), and the photoelectric conversion efficiency of solar radiation are determined. Investigations are performed at illumination intensities corresponding to operation under concentrated radiation. Decreased temperatures facilitate the selection of samples with the minimal “parasitic” potential barriers. The influence of excitationtransfer processes from a cascade into a cascade is estimated by means of secondary luminescent radiation. The highest photoelectric conversion efficiency of 52% is measured at a concentration multiplicity of 100 “suns” and a temperature of–160°C.

Photovoltaic converters of laser light with a wavelength of λ = 1550 nm are developed using liquidphase epitaxy (LPE), metal-organic chemical-vapor deposition (MOCVD), and diffusion from the gas phase into the n-GaSb substrate. Photocells with an area of S of 4, 12.2, and 100 mm2 are fabricated and tested. The characteristics of the samples produced by different methods are compared. The monochromatic efficiency is found to be 38.7% for the best converters (with S = 12.2 mm2) at a laser power of 1.4 W.

Photovoltaic laser-power converters for a wavelength of λ = 809 nm are developed and fabricated on the basis of single-junction AlGaAs/GaAs structures grown by metal-organic vapor-phase epitaxy. The parameters of the photovoltaic structure constituted by an optical “window” and a cladding layer are optimized by mathematical simulation. Photovoltaic converters with areas of S = 10.2 and 12.2 mm2 and 4 cm2 are fabricated and studied. For photocells with S = 10.2 mm2, the monochromatic efficiency (η) was 60% at a current density of 5.9 A/cm2. A photovoltaic module with a working voltage of 4 V (η = 56.3% at 0.34 A/cm2) is assembled.

Results obtained in the development of a metal-organic vapor-phase epitaxy (MOVPE) technology and in studies of the electrical parameters of photovoltaic converters based on heterostructures in the InP/InGaAsP system for the spectral range 0.95–1.2 μm are presented. A MOVPE technique is developed for obtaining and doping InGaAsP solid solutions around the spinodal dissociation region with a band-gap width of about 1.0 eV. Photovoltaic converters of 1000-× concentrated sunlight are fabricated.

New-generation concentrator modules use III–V nanoheterostructure cascade solar cells the efficiency of which can be raised to 50% for the number of cascades exceeding three. To obtain a high overall efficiency of photovoltaic conversion in power plants and extend their service time, it is necessary that the design of the modules be optimal in terms of optics and thermal engineering. In this work, main challenges in designing solar modules, such as optical concentration of radiation and residual heat removal, are considered. The results of pilot works that have been recently done in the Ioffe Physical Technical Institute are primarily reported.

The photoelectric characteristics of triple-junction InGaP/Ga(In)As/Ge solar cells are studied in relation to the method used to form the photocell chip. It is shown that the application of a postgrowth technique developed in the study for separating a nanoheterostructure into chips in a single process makes it possible to improve the quality of passivation of the chip edges, which diminishes the surface leakage currents and makes larger the yield of devices with improved characteristics.

A correlation between the main parameter of a solar cell, the conversion efficiency, and its dark I–V characteristic is investigated. A formula is derived that expresses an increment (decrement) of the efficiency through a decrement (increment) of the current measured at a certain voltage (here at 2.4 V). Relationships are deduced based on which six methods for passivating the sidewalls of triple-junction InGaP/GaAs/Ge heterostructures grown by metal-organic vapor-phase epitaxy are tested to see how they influence the dark I–V characteristic. The influence of different factors, such as post-growth annealing, damaging radiation, etc., on the solar cell efficiency can be estimated by taking the dark I–V characteristic.

The parameters of the concentrating photoelectric modules with triple-junction (InGaP/GaAs/Ge) solar cells whose focusing system contains an original secondary optical element are studied. The element consists of a plane-convex lens in optical contact with the front surface of an intermediate glass plate and a cylindrical waveguide that is located on the rear side of the glass plate above the surface of the solar element. It is demonstrated that the structure of the secondary optical element provides a wide misorientation characteristic of the concentrator and the cylindrical waveguide allows a more uniform radiation density over the surface of the solar cell. The effect of chromatic aberration in the primary and secondary optical systems on the parameters of photoelectric modules is analyzed. It is demonstrated that the presence of waveguides with a length of 3–5 mm leads to effective redistribution of radiation over the surface of the solar cell whereas shorter and longer waveguides provide the local concentration of radiation at the center of the photodetecting area.

High-current solar cells based on gallium antimonide and intended for use in solar modules and systems with solar-spectrum splitting at large solar light concentration ratios, in thermophotovoltaic generators with a high-temperature emitter, and in laser energy converters have been designed and fabricated by the diffusion of zinc from the gas phase. The influence exerted by the thickness of the p+ diffusion layer on the basic characteristics of the solar cell has been studied. The optimal doping profile and the p-n-junction depth providing a high photovoltaic conversion efficiency at photocurrent densities of up to 100 A cm−2 have been determined.

The aim of the study is to apply a method commonly used to determine the efficiency of multi� junction nanoheterostructure III-V solar cells by analysis of the dark current-voltage (I-V) characteristics to such an unconventional semiconducting material as amorphous silicon. aSi:H and aSi:H/ μcSi:H p-i-n structures without a lightscattering sublayer or an an tireflection coating are studied. The results of measure� ments of the dark I-V characteristics demonstrate that the voltage dependence of the current has several exponential portions. The conversion efficiency of solar cells (SCs) is calculated for each portion of the dark I-V characteristic. This yields a dependence of the potential SC efficiency on the generation current density or on the photon flux. The observed agreement between the data derived from the experimental characteris� tics and results of calculations can be considered satisfactory and acceptable, thus the method suggested for measurement and analysis of dark I-V characteristics and tested earlier on SCs based on crystalline III-V compounds acquires a universal nature. The analysis of the characteristics of p-i-n amorphous silicon structures and the calculation of potential efficiencies, based on this analysis, extend the authors' understanding of this class of devices and make it possible to improve the technology and photoconversion efficiency of SCs of this kind.

A concentrator photovoltaic module with spectral splitting of solar radiation is developed. The module is based on a Fresnel lens and two dichroic filters. Solar cells based on AlGaAs and GaAs are grown by low-temperature liquid-phase epitaxy. GaSb photoconverters are fabricated by zinc gas-phase diffusion into a base epitaxial layer or an n-type GaSb substrate. The total efficiency of three solar cells developed for the spectral splitting module reached 39.6% (AM 1.5D spectrum).

Photovoltaic converters based on nGaInP/ n-pGe heterostructures grown by the OMVPE under different conditions of formation of the p-n junction are studied. The heterostructures are intended for use as narrowgap subcells of the GaInP/GaInAs/Ge threejunction solar cells. It is shown that, in Ge p-n junc� tions, along with the diffusion mechanism, the tunneling mechanism of the current flow exists; therefore, the twodiode electrical equivalent circuit of the Ge p-n junction is used. The diode parameters are determined for both mechanisms from the analysis of both dark and "light" current-voltage dependences. It is shown that the elimination of the component of the tunneling current allows one to increase the efficiency of the Ge subcell by ~1% with conversion of nonconcentrated solar radiation. The influence of the tunneling current on the efficiency of the Gebased devices can be in pr actice reduced to zero at photogenerated current density of ~1.5 A/cm 2 due to the use of the concentrated solar radiation.

A prototype compact TPV generator with a propane burner (pressure 2 bar) and a metallic netted emitter has been developed and tested. A photovoltaic generator unit with 24 (1 × 1 cm2) GaSb cells has been fabricated. The fabrication technology of photovoltaic cells has been optimized. It is shown that the data obtained can be used to select the starting bulk material for fabrication of photovoltaic cells with similar output parameters. It has been experimentally demonstrated that, to achieve maximum efficiency, it is necessary, in addition to using photovoltaic cells with similar characteristics, to provide identical conditions of their operation (temperature, illuminance).

A technique for determining a minority carrier’s diffusion length in photoactive III–V layers of solar cells by approximating their spectral characteristics is presented. Single-junction GaAs, Ge and multi-junction GaAs/Ge, GaInP/GaAs, and GaInP/GaInAs/Ge solar cells fabricated by hydride metal-organic vapor-phase epitaxy (H-MOVPE) have been studied. The dependences of the minority carrier diffusion length on the doping level of p-Ge and n-GaAs are determined. It is shown that the parameters of solid-state diffusion of phosphorus atoms to the p-Ge substrate from the n-GaInP nucleation layer are independent of the thickness of the latter within 35–300 nm. It is found that the diffusion length of subcells of multijunction structures in Ga(In)As layers is smaller in comparison with that of single-junction structures.

Two main issues governing the design of a solar concentrator module with triple-junction nano-heterostructure photovoltaic converters (PVCs) are considered: the effective concentration of radiation using Fresnel lenses and effective heat removal from PVCs. By theoretically and experimentally simulating these processes, the design parameters of module’ s elements are determined. A test batch of full-size modules has been fabricated. Each module consists of a front panel of small-size Fresnel lenses (a total of 144 lenses arranged as a 12 × 12 array) and the corresponding number of multilayer InGaP/GaAs/Ge PVCs. The PVCs are mounted on heat-distributing plates and are also integrated into a panel. The efficiency of the concentrator module with a 0.5 × 0.5-m entrance aperture measured under outdoor conditions is 24.3%, which is more than twice as high as the efficiency of standard (concentrator-free) silicon modules. In smaller test modules, the efficiency corrected for the PVC standard temperature (25° C) reaches 26.5%.

Designs of thermophotovoltaic (TPV) generators with infrared emitters heated by concentrated solar radiation are developed, fabricated, and tested. Emitters made of SiC, W, or Ta of various forms and sizes are studied. To the GaSb-based thermophotovoltaic cells, the efficiency of transformation of thermal radiation of W emitters was 19%. The features of operation of two variants of TPV generators, namely, of cylindrical and conical types, are considered. In a demonstration model of the TPV generator consisting of 12 photocells, the output electric power with conversion of the concentrated solar radiation was P = 3.8 W.

The effect of the properties of interfaces with Group-III phosphides on characteristics of GaInP solar cells has been studied. It is shown that the large valence band offset at the p-GaAs/p-AlInP interface imposes fundamental limitations on the use of p-AlInP layers as a wide-band-gap window in p-n structures of solar cells operating at ratios of high solar light concentration. It is demonstrated that characteristics of p-n solar cells can be, in principle, improved by using a double-layer wide-band-gap window constituted by p-Al0.8Ga0.2As and p-(Al0.6Ga0.4)0.51In0.49P layers.

Liquid-phase epitaxy and diffusion from the gas phase have been used to create various kinds of GaSb-based solar cell structures intended for use in cascaded solar-radiation converters. A narrow-gap (GaSb) solar cell was studied in tandem based on a combination of semiconductors GaAs-GaSb (two p-n junctions) and GaInP/GaAs-GaSb (three p-n junctions). The maximum efficiency of photovoltaic conversion in GaSb behind the wide-gap cells is η = 6.5% (at sunlight concentration ratio of 275X, AM1.5D Low AOD spectrum).

Dependence of the efficiency of single-junction and multijunction solar cells on the mechanisms of current flow in photoactive p-n junctions, specifically on the form of the dark current-voltage characteristic J-V, has been studied. The resistanceless J-Vj characteristic (with the series resistance disregarded) of a multijunction solar cell has the same shape as the characteristic of a single-junction cell: both feature a set of exponential portions. This made it possible to develop a unified analytical method for calculating the efficiency of singlejunction and multijunction solar cells. The equation relating the efficiency to the photogenerated current at each portion of the J-Vj characteristic is derived. For p-n junctions in GaAs and GaSb, the following characteristics were measured: the dark J-V characteristic, the dependence of the open-circuit voltage on the illumination intensity P-VOC, and the dependence of the luminescence intensity on the forward current L-J. Calculated dependences of potential efficiency (under idealized condition for equality to unity of external quantum yield) on the photogenerated current for single-junction GaAs and GaSb solar cells and a GaAs/GaSb tandem are plotted. The form of these dependences corresponds to the shape of J-Vj characteristics: there are the diffusion- and recombination-related portions; in some cases, the tunneling-trapping portion is also observed. At low degrees of concentration of solar radiation (C < 10), an appreciable contribution to photogenerated current is made by recombination component. It is an increase in this component in the case of irradiation with 6.78-MeV protons or 1-MeV electrons that brings about a decrease in the efficiency of conversion of unconcentrated solar radiation.

Using the Hall method, regularities of Te doping of GaSb grown by the Czochralski method and by liquid-phase epitaxy (LPE) are studied. Optimum epitaxial conditions that enable the growth of Te-doped GaSb layers with higher carrier mobilities than the bulk Czochralski-grown GaSb are determined. Possibilities of improvement of output parameters of photoconverters obtained by diffusion of Zn into n-GaSb from the gas phase and by LPE are discussed.

The analysis of photoelectrical properties of heterostructure solar cells biased on GaInP is performed using a numerical modelling. The influence of AlInP/GaInP and AlGaAs/GaInP interface parameters and properties of AlInP layer on solar cells characteristics is shown. In particular, a crucial role of the band offsets and of interface states in defining the solar cell efficiency is demonstrated. The observed difference in photovoltaic performance of p–n versus n–p junctions is explained in terms of the parameters outlined above. The simulation results are supported by experimental data.

This study was aimed at the development of a method for detection of colonies of nuclease-secreting marine bacteria. The BAL nuclease-producing marine bacterium Pseudoalteromonas espejiana BAL-31 was used as the test object. A new method was developed involving the congo red (CR) anionic dye. The P. espejiana culture was plated on nutrient agar with CR and denatured DNA. In such media, CR was found to form complexes with DNA. After two days of incubation at 30°C, halos were found around the P. espejiana colonies. No halos appeared when DNA was not introduced, when BAL nuclease was inactivated, or when the plates were inoculated with Escherichia coli. It was concluded that the halos around the colonies indicated nuclease secretion. The halos were shown to result from the coagulation of CR released after digestion of the CR-DNA complex by the nuclease. This method for detection of nuclease-producing colonies can probably be used for all marine bacteria and possibly for halophilic bacteria as well.

The properties of multiple-junction solar cells depend on the properties of the constituent photovoltaic and tunneling p-n junctions. In this study, the properties of the space-charge region for photovoltaic and tunneling p-n junctions were examined using the dark current-voltage characteristics for two semiconductors: GaSb (a narrow-gap semiconductor) and GaAs (a wide-gap semiconductor). The effects of irradiation with protons (the energy of 6.78 MeV and the maximum fluence of 3 × 1012 cm−2), electrons (the energy of 1 MeV and the maximum fluence of 3 × 1016 cm−2), and γ-ray photons (the energy of 1.17–1.33 MeV and the maximum dose of 17 Mrad) on the lifetime of charge carriers in the space-charge region of photovoltaic p-n junctions and on the peak current of connecting tunneling p-n junctions were studied. The coefficients of the damage for the inverse lifetime are determined for photovoltaic p-n junctions. The coefficients of equivalence between the used types of radiation are determined; these coefficients are found to be almost independent, on the order of magnitude, of the type and material of the p-n-junction (and nearly equal for photovoltaic GaAs p-n junctions and tunneling GaAs and GaSb p-n junctions).

Monolithic dual-junction GaInP/GaAs solar cells grown by the MOCVD method were studied. The conditions of the growth of ternary Ga x In1−x P and Al x In1−x P alloys lattice-matched to GaAs are optimized. Technology for fabrication of a tunneling diode with a high peak current density of 207 A/cm2 on the basis of heavily doped n ++-GaAs:Si and p ++-AlGaAs:C layers is developed. Cascade GaInP/GaAs solar cells obtained as a result of relevant studies featuring a good efficiency of the solar-energy conversion both for space and terrestrial applications. The maximum value of the GaInP/GaAs solar-cell efficiency was 30.03% (at AM1.5D, 40 suns).

Electrical properties of GaSb epitaxial layers grown by the MOCVD method under various conditions are studied. It is shown that the morphology of the layers, free-carrier concentration, and carrier mobility depend on the molar flux ratio TMSb/TEGa. The structure and luminescent properties of the layers are analyzed at 77 K. The dependences of the growth rate, carrier concentration, and carrier mobility on the III–V ratio in the gas phase are obtained. An abrupt decrease in carrier mobility at TMSb/TEGa ≈ 3 is observed.

DNA of bacteriophage PM2 is a convenient test object for studying DNA-damaging genotoxic agents. The extent of DNA damage can be estimated by the ability of damaged DNA for transfection of host cells, marine bacterium Pseudoalteromonas espejiana (Pae), str. BAL-31. The efficiency of transfection of Pae lines maintained for long periods without freezing was found to be very low upon the use of a widely accepted transfection method developed by van der Schans et al. (1971). Such cultures grown in a medium with 10 mM Ca2+ standard for Pae contained cell aggregates and exopolymer material. Pae was found to be capable of growing in a medium without the calcium supplement in the presence of chelator EGTA (low-calcium medium, LCM). After growth in LCM, cells did not aggregate, cultures lacked the activity of nuclease BAL, and transfection efficiency of cells grown in LCM drastically increased. Based on these results, a novel procedure of transfection with an efficiency of 2 × 104−2 × 105 infectious centers per microgram of PM2 DNA was developed.

Concentrator technology is considered as a lower cost alternative to the “flat” solar arrays. For high concentration ratios (500× and higher) the use of high-efficiency III–V solar cells is very promising and can provide reduced cell cost contribution to the cost of an installation. The efficiencies of 25–27% were achieved for the single-junction AlGaAs/GaAs solar cells under 500–1500 suns, AM1.5d. These cells are applied in the concentrator modules based on a concept of the small-aperture refractive concentrators. A modified structure of the high concentration “all-glass” PV modules with III–V solar cells is proposed. In the “all-glass” module design, the secondary small-aperture smooth surface lenses arranged in an intermediate composite (glass–silicone) panel be inserted between a panel of the primary composite Fresnel lens concentrators and a panel of the solar cells. Such a design allows fabricating the modules of large total area (up to 0.5×1 m2) and improving environmental protection of the cells. The cells as small as 1.2 mm in designated area diameter operating at very high concentration ratio (more than 1000×) can be used in the developed solar PV modules. Also, solar thermophotovoltaics (TPV) is discussed and results of the narrow-gap GaSb and GaAs/Ge cell development for TPV receivers are presented.

The potential of the thermophotovoltaic conversion of thermal and solar energy to electricity using narrow-gap semiconductor photoconverters is shown. Liquid-phase epitaxy, metal-organic chemical vapor deposition, and Zn diffusion from the vapor phase are used to fabricate thermophotovoltaic converters based on GaSb and GaAs/Ge structures and characterized by increased values of both photocurrent and open-circuit voltage. This circumstance made it possible to obtain thermophotovoltaic cells that were based on the aforementioned structures and had efficiencies of 25% (GaSb) and 16% (GaAs/Ge) at a blackbody-radiation temperature of T=1473 K under the condition of 100% return of low-energy photons to the emitter.