Evaluating interface roughness and micro-fluctuation potential of InAs/GaSb superlattices by mid-infrared magnetophotoluminescence

Abstract

Interface roughness of the InAs/GaSb type-II superlattice (T2SL) is a key issue for infrared photodetector performance. While numerous studies have been performed on interface roughness from the atomic perspective, the relation with photoelectric performance is not yet straightforward. In this study, we carry out mid-infrared magnetophotoluminescence (MPL) measurements on InAs/GaSb T2SLs with a nominally identical period structure. Micro-fluctuation potential and effective interface roughness are evaluated and compared by the photoluminescence linewidth evolution. The analyses agree qualitatively with the x-ray diffraction linewidth and resolve two types of interface roughness quantitatively: the long lateral-length fluctuation, which is exacerbated by the lattice-mismatch, and the short lateral-length fluctuation, which is related possibly to interfacial atomic exchange. These results suggest that MPL can be an effective tool for evaluating the micro-fluctuation potential of InAs/GaSb T2SLs and understanding the effects of interface roughness on electro-optical performance.