GazIn1-zPxAsySb1-x-y/InSb heterostructures for thermophotovoltaic converters

Abstract

The GaInPAsSb solid solution is used to create optoelectronic devices in the visible and IR spectral ranges. A necessary condition for increasing the efficiency of thermophotoelectric converters is a high degree of crystallographic perfection of heterostructures. However, the preparation of GaInPAsSb solid solutions is associated with a number of difficulties. It has wide areas of immiscibility, a high probability of the formation of non-stoichiometric compositions. The aim of this work is to grow GaInPAsSb/InSb heterostructures with high photoluminescent characteristics. GaInPAsSb/InSb heterostructures were grown by the method of zone recrystallization with a temperature gradient in the temperature range 753-873 K, determined from the study of liquidus temperatures. The manufacturing technique consists in the crystallization of a solution-melt of pure In, Ga, P, Sb, As components on an InSb substrate. A liquid zone with a thickness of 20-150 nm replenishment of liquid phase InPSbAs polycrystalline to create a uniform distribution of components over the thickness of the epitaxial layer. Based on the analysis of "liquid-solid" phase equilibria within the framework of the simple solution model, the technological parameters of the heteroepitaxial growth of GaInPAsSb solid solutions in the composition range $0.01\le x\le 0.30$, $0.01\le y\le 0.45$, $0.01\le z\le 0.60$. With an increase in the concentration of phosphorus in the solid solution, the mismatch in the lattice periods of the layer and substrate $\delta a$ increases. However, the mismatch between the lattice periods of the substrate and the solid solution layer by a value of $\delta a\ge 0.0$% causes stresses at the heterointerface, which prevent spinodal decomposition, increasing the region of existence of GaInPAsSb solutions. The photoluminescence spectra of GaInAsSb/InSb and GaInPAsSb/InSb heterostructures are compared with the active region in the layer. It is shown that the addition of phosphorus to GaInAsSb leads to an increase in the intensity and a decrease in the emission bandwidth at half the height of the peaks. This indicates an improvement in the crystalline properties of the films. As a result, the use of five-component GaInPAsSb solid solutions as the active area of thermophotoelectric converters makes it possible to increase the external quantum efficiency to 0.95 in the spectral range 2700-4700 nm.