The possibility of manufacturing photovoltaic converter structures due to solid-phase reactions of substitution of Sb atoms in GaSb semiconductor wafers with As or P atoms, with simultaneous diffusion of Zn, is demonstrated.

Optimized photoconverters for operation under high-power laser radiation in the green-red spectral range based on MOCVD-grown GaInP/GaAs heterostructures are fabricated. The Au(Ge)/Ni/Au and Pd/Ge/Au contact systems have been studied to form the front contact grid of devices. As a result, the laser photoconverter with a Pd/Ge/Au contact showed an efficiency of more than 50% up to an incident radiation power density of 30 W/cm 2 with a maximum value of 54.4% under 7 W/cm 2 for laser line with wavelength of 600 nm. Keywords: photoconverter, laser radiation, MOCVD, efficiency, spectral sensitivity.

GaInP-based laser power converters (LPC) structure grown by MOVPE and device chip design have been optimized for operation under high-power lasers of the green-red spectral range. Light I-V curves records have shown the performance of the LPC at up to 40-50 W/cm2 of incident power densities. The highest level data were obtained for 532, 600, and 633 nm power laser lines: 44.3%, 46.7%, and 40.6% under 13-16 W/cm2, respectively. LPC demonstrated an efficiency of more than 40% at the incident laser radiation power density elevated up to 40-50 W/cm2. Keywords: laser photoconverter, MOVPE, efficiency, spectral response.

The effect of positioning of the In0.8Ga0.2As quantum dots (QDs) array in the i-region of the solar cell (SC) on its photogenerated current and dark saturation currents, which determine the device operating voltage, have been investigated. It was found out that the indicated photoelectric characteristics depend on the location of the QD array relative to the electric field of the p-n junction. The displacement of the QD array to the boundary of the weakly doped base leads to a decrease in the photogenerated current. But at the same time, the voltage drop effect, which is well-known for nanoheterostructural SC, is minimal. Keywords: solar cells, quantum dots, dark saturation current

Developed and investigated are IR (850 nm) light-emitting diodes based on AlGaAs/Ga(In)As heterostractures grown by the MOCVD technique with multiple quantum wells in the active region and with a double optical reflector consisted of a multilayer Al0.9Ga0.1As/Al0.1Ga0.9As Bragg heterostructure and an Ag mirror layer. Light-emitting diodes with the external quantum efficiency EQE = 37.5

Utilizing performed research, photoelectric converters of narrow-band radiation (λ~1.0-1.3 μm) based on InGaAsP/InP heterostructures with an epitaxial p-n junction have been developed and created. Technological regimes that apply of for creating high-quality layers of quaternary InGaAsP solid solutions isoperiodic to indium phosphide in a wide range of compositions by liquid-phase epitaxy have been determined. Keywords: photovoltaic converters, narrowband radiation, InGaAsP, InP, LPE, heterostructures.

The paper presents a promising solution for photovoltaic modules that provides overcoming the main conceptual limitation for the concentrator concept in photovoltaics—the impossibility to convert diffused (scattered) solar radiation coming to the panel of sunlight concentrators. The design of a hybrid concentrator-planar photovoltaic module based on heterostructure solar cells: A3B5 triple-junction and Si-HJT is presented. The results of initial outdoor studies of the module output characteristics are discussed and estimates of its energy efficiency are given.

The efficiency of GaInP/GaAs/InxGa1-xAs triple-junction solar cells obtained by replacing (in the widely used "classical" GaInP / GaAs / Ge heterostructure) the lower germanium with InxGa1-xAs subcell formed using the metamorphic growth technology has been investigated. Based on an original approach, the optimal indium concentration in the narrow-gap subcell has been found. The main parameters of InxGa1-xAs subcells with an indium concentration from x=0.11 to 0.36 were determined and were used to calculate the IV characteristics of GaInP/GaAs/InxGa1-xAs solar cells. It has been determined that at x=0.28 the efficiency of the triple-junction solar cell increases by 3.4% (abs) in comparison with the "classical" solar cell, reaching a value of 40.3% (AM1.5D). Also it has been shown that the efficiency of such solar cells can be increased up to 41%. Keywords: Multi-junction solar cells, photoconverters, metamorphic buffer. M.Z.Shvarts,

In this work, we studied the influence of GaP compensating layers on the characteristics of GaAs solar cells with InGaAs quantum dot arrays. An increase in the overall level of quantum efficiency in the absorption range of quantum dots (870-1000 nm) by more than 10% has been demonstrated when GaP layers are embedded in GaAs intermediate layer (spacer) of a quantum dot array. It was also shown that in this case a noticeable increase in the open-circuit voltage can be achieved at high solar concentration.

The paper presents a promising solution for photovoltaic modules that provides overcoming the main conceptual limitation for the concentrator concept in photovoltaics - the impossibility to convert diffused (scattered) solar radiation coming to the panel of sunlight concentrators. The design of a hybrid concentrator-planar photovoltaic module based on heterostructure solar cells: A3B5 triple-junction and Si-HJT is presented. The results of initial outdoor studies of the module output characteristics are discussed and estimates of its energy efficiency are given.

Photovoltaic converters of high-power (lambda = 800-860 nm, E-LR = 150-550 W/cm(2)) laser radiation (PhotoVoltaic Laser Power Converters - PVLPCs) based on AlGaAs/GaAs heterostructures grown by metalorganic vapor-phase epitaxy have been developed. To increase the output voltage, the space charge region of p-GaAs/n-AlxGa1-4As heterojunction was shifted to the n-AlxGa1-xAs wide-gap layer with a gradual "x". The technology for embedding a rear reflector based on TiOx/SiO2/Ag into the photovoltaic converter structure by "transferring" the heterostructure to a supporting substrate and the method of bonding to form a monolithic structure of the PVLPC has been elaborated. To operate the heterostructures at an increased power density of laser radiation, they have been designed to eliminate possible potential barriers at the heterointerfaces and the frontal contact topology with a high density of the metal grid (50 mu m and 125 mu m contact pitch are under consideration) has been employed. PVLPCs with efficiency of 62% were obtained at the power density of monochromatic radiation (lambda = 850 nm) E-LR = 170 W/cm(2). The finger pitch of 50 mu m allows keeping efficiency more than 56% even with a fivefold increase in laser radiation (up to E-LR = 500 W/cm(2)).

Изготовлены оптимизированные фотопреобразователи на основе гетероструктур GaInP/GaAs, выращенных методом металлоорганической газофазной эпитаксии, для работы с лазерным излучением высокой мощности зелено-красного спектрального диапазона. Для формирования лицевой контактной сетки приборов исследованы контактные системы Au(Ge)/Ni/Au и Pd/Ge/Au. В результате фотопреобразователь лазерной линии с длиной волны 600 nm с Pd/Ge/Au-контактом демонстрировал КПД более 50% вплоть до плотности мощности падающего излучения 30 W/cm 2 с максимальным значением 54.4% при 7 W/cm 2 . Ключевые слова: фотопреобразователь, лазерное излучение, металлоорганическая газофазная эпитаксия (МОСГФЭ), КПД, спектральная чувствительность.

Samples of heterostructures made on the basis of semiconductor wafers of binary compounds GaAs, GaSb and InAs as a result of substitution of Group V elements of atoms by atoms of other Group V elements supplied in the form of vapors, including simultaneous Zn diffusion are studied. The possibility of using the obtained structures to make a photoelectric converter is demonstrated.

A combined module that combines a concentrator with planar photovoltaic circuits provides energy conversion of both parts of global terrestrial radiation: direct sunlight by concentrator solar cells and scattered (diffuse) sunlight by planar (non-concentrator) photoconverters. The decrease in Fresnel lens concentrating ability is usually associated with imperfections in the optical refractive surfaces, where some part of the direct light, which arrives normal to the surface of the Fresnel lens and is intended to be concentrated, becomes scattered and directed off the highly efficient concentrator solar cell. The diffuse light flux propagates inside the volume of the combined photovoltaic module. This flux undergoes multiple reflections from the structural elements, is partially absorbed, and ultimately reaches the photoconverters of the planar circuit. Thus, two types of diffuse light impinge the planar circuit: "external" from the atmosphere and "internal" produced by the Fresnel lens from direct light. This Letter proposes a method for determining the diffuse properties of sunlight concentrators such as Fresnel lens.

Developed and investigated are IR (850 nm) light-emitting diodes based on AlGaAs/Ga(In)As heterostructures grown by the MOCVD technique with multiple quantum wells in the active region and with a double optical reflector consisted of a multilayer Al0.9Ga0.1As/Al0.1Ga0.9As Bragg heterostructure and an Ag mirror layer. Light-emitting diodes with the external quantum efficiency EQE=37.5% at current densities greater than >10 A/cm2 have been fabricated. Keywords: IR light-emitting diode, AlGaAs/GaAs heterostructure, Bragg reflector, InGaAs quantum wells.

The possibility of manufacturing photovoltaic converter structures due to solid-phase reactions of substitution of Sb atoms in GaSb semiconductor wafers with As or P atoms, with simultaneous diffusion of Zn, is demonstrated.

GaInP-based laser power converters (LPC) structure grown by MOVPE and device chip design have been optimized for operation under high-power lasers of the green-red spectral range. Light IV curves records have shown the performance of the LPC up to 40-50 W/cm2 of incident power densities. The highest level data were obtained for 532 nm, 600 nm, and 633 nm power laser lines: 44.3%, 46.7%, and 40.6% under 13-16 W/cm2, respectively. LPC demonstrated an efficiency of more than 40% at elevated up to 40-50 W/cm2 of the incident laser power density.

GaSb-based thermophotovoltaic converters for a selective mantle-type Y 2 O 3 emitter coated with rare-earth oxides Er 2 O 3 /Yb 2 O 3 are investigated. Matching of the converter spectral response with the peak emitter-radiation wavelength λ = 1540 nm provides a thermophotovoltaic conversion efficiency of more than 26% (0.4 W).

Temperature dependencies of the refractive indices, n, for InxGa1-xAs and InxAl1-xAs metamorphic layers with x=0.06-0.25 have been determined. For this purpose, we performed variable-temperature (80 to 400 K) measurements of the specular reflection coefficient using custom distributed-Bragg-reflector structures in the spectral range from 0.8 µm to 2.2 µm. All the compositions exhibited a nearly linear temperature dependence of n. For InxGa1-xAs, the temperature coefficient (dn/dT) increases from 2.0⋅10-4K-1 for x=0.06 to 4.5⋅10-4K-1 at x=0.25. In turn, the temperature coefficient of the InxAl1-xAs refractive index stays at the level of (1.7-2.0)⋅10-4K-1 at the considered indium contents.

In the work, the effect of In0.8Ga0.2As quantum dots position in the i-region of a GaAs solar cell on its spectral and photoelectric characteristics has been investigated. Three solar cell structures were obtained by metal-organic vapor-phase epitaxy, in which layers of quantum dots were placed in the middle of the i-region and also have been shifted to the base and the emitter. As a result, it has been shown that the solar cell with a quantum dot array shifted to the base demonstrates the smallest open-circuit voltage drop and, accordingly, a higher efficiency value.