Microstructural characterization of thick ZnTe epilayers grown on GaSb, InAs, InP and GaAs (100) substrates

This paper describes a comprehensive investigation of thick ZnTe epilayers (∼2.4 μm) grown under virtually identical conditions on GaSb, InAs, InP and GaAs (1 0 0) substrates using molecular beam epitaxy. Cross-section transmission electron micrographs of the different heterostructures showed greatly reduced defect densities away from the interface region. High-resolution electron micrographs revealed a highly coherent interface with isolated dislocations for the ZnTe/GaSb sample, and showed extensive areas with well-separated interfacial misfit dislocations for the ZnTe/InAs sample. Lomer edge dislocations with Burgers’ vector of (1/2) a 〈1 1 0〉, as well as perfect 60° dislocations, were identified at the interfaces of the ZnTe/InP and ZnTe/GaAs samples. Digital image processing based on lattice–fringe images was also used to analyze the spatial distribution of misfit dislocations at the hetero-interfaces, in particular to estimate the amount of residual strain.