Reduction of Threading Dislocation Density in an (InAs)1(GaAs)1 Strained Short-Period Superlattice by Atomic Hydrogen Irradiation

Abstract

The generation process of dislocations as well as the initial growth mechanism were investigated in the growth of an (InAs)1(GaAs)1 strained short-period superlattice (SSPS) on a GaAs (001) substrate under atomic hydrogen (H) irradiation. A two-dimensional (2D) growth mode was maintained even after lattice relaxation occurred for growth at 350° C. On the other hand, the growth mode changed from 2D to a three-dimensional (3D) one without atomic H irradiation. The threading dislocation density was remarkably reduced and the critical thickness was markedly increased by atomic H irradiation. Misfit dislocations propagating along the <110> and <100> directions were generated at the heterointerface. Such effects disappeared for growth at 500° C, where the atomic H atoms desorb from the growing surface. It was also found that 3D growth was more effectively suppressed in the growth of (InAs)1(GaAs)1 SSPS than in a In0.5Ga0.5As alloy which has the same average In composition as that of the SSPS.