Electronic states and interband tunneling conditions in type-II quantum well heterostructures

Abstract

Type-II quantum well (QW) heterostructures based on the InAs/GaSb/AlSb material system have important applications in interband tunneling and midinfrared optoelectronic devices. From the perspective of interband tunneling conditions in widely used type-II QWs such as N-QW, W-QW, and M-QW structures, this work studies how energy levels for electronic and light-hole states are varied with various combinations of semiconductor material layers. Using a two-band model, analytical expressions are derived for the transition well widths that correspond to the critical layer thicknesses for bound- or quasibound states to appear in the interband tunneling region in type-II heterostructures, which provide meaningful connections to semiconductor material parameters. Calculations of transition well widths are carried out for several InAs/GaSb/AlSb-based type-II QW structures. The results and understanding gained from the study may be helpful in designing and developing midinfrared optoelectronic devices such as interband cascade lasers, photodetectors, and thermophotovoltaic cells.