Composition and surface deformation variance in highly strained InxGa1−xSb structures on (100) GaSb

Abstract

InxGa1−xSb is a ternary semiconductor material that offers excellent electronic properties as well as a widely tunable bandgap range (1.7–7.3 μm). However, because of the potentially large lattice mismatch between InxGa1−xSb and GaSb (up to ∼6%), it is inherently difficult to produce large area, high-quality, defect-free InxGa1−xSb epilayers. Studying crystal deformation processes that ultimately enable gliding dislocations in InxGa1−xSb epilayers, as well as the morphologies that result from these processes, is critical for controlling quantum properties in InxGa1−xSb devices. In this study, InxGa1−xSb nanostructures were produced by a solid-source molecular beam epitaxy on undoped GaSb (100) substrates and were examined using various techniques including scanning electron microscopy, energy dispersive spectroscopy, and (micro) Raman spectroscopy. Characterization data demonstrates that with increasing lattice mismatch (compressive strain), there are two distinct regions across the sample, specifically along the 〈110〉 dislocation direction: those with and without epilayer strain. Both regions can be exploited and exhibit high-quality single crystal material, but the strained regions also consist of a wetting layer, strained alloys, and clusters. Epilayer strain, lateral compositional gradients, and biaxial stress were analyzed as a function of Raman shift in these layers and revealed dependencies on the influence of dislocation slip planes.