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Information × Registration Number 0201U005259, 0100U006651 , R & D reports Title Theoretical modelling and technology development of high-efficient tandem solar cells on the basis of multilayer heterostructures of gallium arsenide and its solid solutions. popup.stage_title Head Torchyns'ka T.V., Registration Date 08-06-2001 Organization Institute of Semiconductor Physics popup.description2 Investigated objects - AlxGa1-xAs/GaAs, AlxGa1-xAs/InxGa1-xAs/GaAs, InxGa1-xP/GaAs heterostructures. Project goal - theoretical modelling and technology development of obtaining of radiation-proof and high efficiency multilayer cascade photoelectric cells on the basis of А3В5 semiconductors, namely - AlxGa1-xAs/GaAs, AlxGa1-xAs/InxGa1-xAs/GaAs and InxGa1-xP/GaAs heterostructures, for further making on their basis of a new generation of optoelectronic pairs, photoelectric batteries and solar station with concentrators of solar radiation. Methods of investigation - measurement of photoluminescence (PL), measurement of spectral characteristics, measurement of volt-ampere, watt - volt, lux-ampere characteristics, reflective high-energy electron diffraction , composition analysis by thickness fringe-transmission electron microscopy. The program on parameter optimization of multilayer heterostructures for a computer is designed which is necessary for technology adjustment of necessary structures manufacturin g. The internal stresses in multilayer semiconductor structures are the undesirable factor, which diminish their hardness and operating characteristics in whole. The external appearance of internal stress presence is a heterostructure bend after transition from manufacturing temperature to normal. There is an opportunity to control a level of internal stresses and value of bending of layered structure by means of the relevant select of layer parameters. Such select can be carried out with the help of optimization methods. The program above mentioned allows, varying parameters, to receive optimum structures of cells. Some structures of the optimized photoelectric cells on basis of AlxGa1-xAs/GaAs heterostructures are grown by liquid- phase epitaxy. For technology optimization of heterostructure production for solar photoelectric cells two technological modes of a liquid-phase epitaxy were selected: low-temperature and high-temperature. The measured characteristics of solar cells have shown, that they meet the calculated optimum parameters. The theoretical analysis of AlxGa1-xAs/InxGa1-xAs/GaAs solar tandem cell is carried out. The cell construction is composed of wide-band and narrow-band junctions, electrically jointed by means of the tunnel diode which has been carried out as a single unit in monolithic structure. The design contain also a window layer to minimize losses due to surface recombination. The involved analytical method is an approximate formal solution of transport equations with the main solution obtained for the integrated form of the continuity equation. Efficiency of the proposed device for АМ0 sunlight level is of 32 %. The efficiencies as functions of temperature are compared. Up to 400K efficiencies for АМ1, 1.5, 2, 3, and 5 are higher than the efficiency for АМ0; the АМ0 efficiency is higher at temperatures > 400K. Curves show, that efficiency increases up to 400K with increase of value АМ to АМ3, and then it remains relatively constant above АМ3. At temperatures > 400K efficiency diminishes slightly to АМ1, and it is relatively constant above АМ1. It is possible to explain behaviour of efficiency in two temperature areas (up to 400К and above 400К) that portion of quantum flux in short-range infrared range of spectrum is more, than that in a blue-range range with magnification of value АМ from 0 to, approximately, 3. Аs a result, it yields smaller absorbtion of quantums in window layers (AlGaAs) and further lowering of losses due to surface recombination. The optimal growth procedure of GaInP/GaAs heterointerface by molecular- beam epitaxy has been investigated. The interface quality is critical factor for obtaining high-efficient GaAs solar cells with a GaInP barrier layer because minority carrier lifetime depends strongly on the interface structure. Reflective High-Energy Electron Diffraction observation during the growth across the GaInP/GaAs heterointerface shown that the phosphorus atoms are replaced by arsenic atoms in the near-interface region of the GaInP layer, and a transient layer a cting as a carrier trap is formed. Introduction of a GaP layer into the interface was found to be effective in reducing carrier loss. This layer is preferable for improving optical properties of the GaInP/GaAs heterointerface as well. From composition analysis by thickness fringe-transmission electron microscopy images, it was also found that the optimum thickness of inserted GaP layer to suppress the generation of misfit dislocations as well as the formation of a low-band-gap transition layer was found to be 1 nm. The optimized photoelectric cells on basis of a InGaР/GaAs heterostructure are obtained by molecular- beam epitaxy. For technology of reception of heterostructures the low-temperature mode of a liquid-phase epitaxy was selected. The measured characteristics of solar cells have shown the predicted optimum parameters. Product Description popup.authors popup.nrat_date 2020-04-02 Close