Electronic energy levels inInxGa1−xAs/InP strained-layer superlattices

Abstract

We use intentionally-lattice-mismatched superlattices of ${\mathrm{In}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As/InP, where 0.3<x<0.8, to study the energy levels of confined-particle states characteristic of strained-layer superlattices. We demonstrate that the energy difference between the lowest heavy- and light-hole exciton levels of ${\mathrm{In}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As quantum wells changes continuously with strain. For x<0.44 the exciton levels switch positions so that the light hole becomes the lower-energy state. The experimental results can be modeled with very high accuracy over the entire range of In compositions studied with a phenomenological deformation-potential theory.