Applied Physics Seminar: Influence of Alloy Composition and Strain on Band Alignments at Semiconductor Heterostructures

Compound semiconductor heterostructures are useful for a variety of energy conversion and optoelectronic applications. For example, heterostructures with a nested (type I) band alignment, which facilitates electron-hole recombination, are useful for light-emitting devices. On the other hand, a staggered (type II) band alignmentenables spatial separation of charge carriers, an advantage for charge-based memory and solar cell devices. Often, quantum structures are predicted to undergo strain and/or composition induced transitions from type I to type II offsets. However, there are conflicting reports in the literature regarding the experimental signature for the type I to type II transition, and a predictive framework for the composition and strain dependence of the band alignment is yet to be developed. In this talk, I will discuss our progress in unraveling the interplay between composition, strain, and band-alignments, in a selection of systems, including binaries and ternaries of GaAs: Bi, N, Sb, all prepared epitaxially.