Ultra-short period Ga-free superlattice growth on GaSb

Abstract

This work describes a thorough investigation of the structural properties of intended binary InAs/InSb strained layer superlattices (SLS) on GaSb substrates for infrared detection. The designed periods were as short as possible, with the InSb layers approaching one to two molecular monolayers. None of the examined growth conditions produced complete InSb layers. All samples showed a significant loss of Sb. The Sb that was incorporated was found to exhibit a spread in the growth direction, mainly due to step formation, and secondly due to forward diffusion. All structures, therefore became an InAs1-xSbx/InAs1-ySby SLS. The intended InAs layer had a Sb composition of x ∼ 0.003–0.010 and the intended InSb layer had composition y, ranging from ∼0.24–0.43. All terrace steps appeared to be in the same direction, resulting in a weak tilt of the SLS relative to the substrate normal. We discuss the implications for growth of high-Sb-concentration InAsSb/InAs structures.