Optimization of mid-infrared InAs∕GaSb type-II superlattices

Abstract

The effect of small changes in GaSb layer width on the photoresponse spectrum of 20.5ÅInAs∕InSb-interfaces∕XÅ GaSb type-II superlattice (SL) suitable for mid-infrared detection was investigated. By decreasing the GaSb width X from 27 to 18Å, the cut-off wavelength was increased from 4.03 to 4.55μm. This decrease of the SL band gap and other effects of the design changes on photoresponse spectrum with narrower GaSb layers are explained by a nonperturbative, modified envelope function approximation calculation that includes the interface coupling of heavy, light, and spin–orbit holes resulting from the in-plane asymmetry at InAs∕GaSb interfaces.