Microstructure of the GaSb-on-InAs heterojunction examined with cross-sectional scanning tunneling microscopy

Abstract

We have investigated the atomic-scale morphology and composition of the GaSb-on-InAs heterojunction with cross-sectional scanning tunneling microscopy, and find a new “white-noise” component in the wave-vector-dependent roughness spectrum under epitaxial growth conditions routinely employed for type-II quantum well and interband cascade lasers. This phenomenon is associated with random substitutional defects at the interface whose concentration exceeds that due to bulk cross incorporation. We propose these defects originate from the thermodynamically favored but incomplete replacement of As by Sb at the InAs surface during anion exchange.