Band offsets for strained InxGa1-xAs/AlyGa1-yAs heterointerfaces

Abstract

Valence-band offsets for pseudomorphically strained InxGa1-xAs/AlyGa1-yAs ternary-on-ternary heterointerfaces have been calculated as a function of both indium and aluminum content. The unstrained valence-band offsets were considered within the virtual-crystal approximation, accounting for band parabolicity and alloy mixing. Strain was introduced as a perturbation with composition-dependent material parameters, and is shown to strongly influence the valence-band offsets. Equivalent conduction-band-offset ratios are shown to be nonconstant and extremely variable as a function of both In and Al content and are compared to recent experimental data. Various formalisms to calculate the partitioning coefficient for hydrostatic band-gap deformation are presented and discussed, and our analysis indicates that a significant portion of the band-gap variation induced by hydrostatic strain resides in the valence band. Investigation of the spin-split light-hole band level under strain indicates that both type-I and type-II heterointerfaces are achievable with an appropriate choice of compositions. © 1990 The American Physical Society.