Transition levels of intrinsic defects in type-Ⅱ InAs/InAs_(0.5)Sb_(0.5) strained-layer superlattices

摘要

We report a first-principles study of the formation energies and transition energy levels of intrinsic point defects, including In and As vacancies, antisites, and interstitials, in the InAs and InAs0.5Sb0.5 regions of the type-II InAs/InAs0.5Sb0.5 strained-layer superlattices (SLSs). Both strain and the quantum confinement effects are thoroughly studied. The transition levels of the defects calculated from the strained bulk InAs and InAsSb are aligned to the band edge states of the SLS. The calculations reveal that both the strain and the change of the SLS band edges have significant effects on the transition levels and change in turn the role of these defects in the recombination of carriers through the Shockley-Read-Hall mechanism.