Defects in Cd x Hg1 − x Te-based heterostructures grown by molecular beam epitaxy on GaAs(310) substrates

Abstract

Cd x Hg1 − x Te-based epitaxial heterostructures grown on [310]-oriented GaAs substrates by molecular beam epitaxy have been studied by atomic force, scanning electron, and high-resolution field emission microscopy. A mechanism of defect formation has been proposed. The microstructure of the epilayer has been investigated in greatest detail. We have analyzed the key features of V-defect formation, in particular using depth profiling of the heterostructures by ion etching. A comparative analysis of the elemental compositions of V-defects and a defect-free region has been performed. The results indicate that, in the central part of the V-defects, the excess tellurium content is ∼2.5% and mercury deficiency is ∼3%. V-defect formation in the heterostructures is related to tellurium precipitation, which initiates nucleation of polycrystalline clusters and dislocation generation in adjacent regions.