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High-speed photodetectors (PDs) based on InGaAs/GaAs quantum well-dot (QWD) nanostructures with the frontal-end and back-end input of radiation have been studied. A PD with 40 rows of QWDs exhibited a spectral responsivity of up to 0.4 A/W in the 950–1100 nm optical range at a –5-V bias voltage. The decay time constant of pulsed response for PDs with an input area of 1.4 × 10–4 cm2 was ~250 ps.

Results are reported of using subcontact layers with energy gap width Eg of 0.35 to 0.8 eV for obtaining low-resistivity electrical contacts to p-InP. An experimental dependence of the contact resistance on Eg of the subcontact material InxGa1 – xAs was obtained.

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 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

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