Misfit strains in epitaxial heterostructures based on semiconducting solid solutions of A4B6 compounds

Abstract

Misfit strains in three lattice-matched epitaxial heterostructures Pb0.8Sn0.2Te-PbSe0.08Te0.92, Pb0.8Sn0.2Te-PbS0.05Te0.95, Pb0.93Sn0.07Se-PbS0.05Se0.95 have been studied. The epilayers of these heterostructures are sensitive to infrared radiation in the range of 8-14 mu m, while the substrates can be used as detectors of radiation in the range of 3-5 mu m. The estimation of the mechanical strains was based on the determination of the lattice parameter profiles in transient layers of the heterostructures using Auger spectroscopy analysis and on measurements of elastic moduli of the structure components. The maximum value of the strains found in the Pb0.93Sn0.07Se-PbS0.05Se0.95 heteropair was 3.4*107 Pa, in Pb0.8Sn0.2Te-PbSe0.08Te0.92 it was 108 Pa, and in Pb0.8Sn0.2Te-PbS0.05Te0.05 it was 4.4*108 Pa. Comparing with the elasticity limit of A4B6 compounds, one can state that even in the lattice-matched heterostructures the interdiffusion of components as well as the difference in the elastic properties of the epilayer and substrate could lead to inelastic deformation in the transient layer and to the generation of the misfit dislocation network.