Defect Structures in Epitaxially Grown InAs Films on InP Substrates

Abstract

In this paper we study the lattice-mismatch induced defect structures of InAs films grown on semi-insulating InP substrates using metal organic chemical vapor deposition. The defect structure studies were carried out on films of equal total thicknesses but for different duration for nucleation of a layer of InAs deposited at low temperature on the substrate. Misfit strain is caused by the inherent lattice mismatch of approximately three percent and this is partially relieved by the generation of misfit dislocations at the film/substrate interface. Transmission electron microscopy studies show the presence of an intrinsic strain and the generation of thermal etchpits at the heteroepitaxial interface. Our studies show that there is a direct correlation between the density of dislocations generated at the film/substrate interface and the duration of nucleation of the film on the substrate. Dislocation densities at the surface of the InAs films and at the heteroepitaxial interface differed by almost two orders of magnitude. High resolution electron microscopy reveals abrupt and sharp interfaces in films with thick nucleation layers and also confirms that the lattice mismatch is partially accommodated by the generation of misfit dislocations at the film/substrate interface.

Strain relaxation and dislocation introduction in lattice-mismatched InAs/GaP heteroepitaxy

“…The literature contains a few reports of InAs/InP (Ballal et al 1992) and InAs/GaAs (Trampert et al 1995) growth, but these do not attempt to investigate strain relaxation in detail. InAs is a narrow-bandgap compound semiconductor with potential applications in high-speed transistors, infrared defectors and magnetic ®eld-sensing devices.…”