Terahertz band-gap in InAs/GaSb type-II superlattices

We demonstrate theoretically that it is possible to realize terahertz (THz) fundamental band-gap between the electron mini-band in the InAs layer and the heavy-hole mini-band in the GaSb layer in InAs/GaSb based type II superlattices (SLs). The THz band-gap can be tuned by varying the sample growth parameters such as the well widths of the InAs and/or GaSb layers. The presence of such band-gap can result in a strong cut-off of optical absorption at THz frequencies. For typical sample structures, the THz cut-off of the optical absorption depends strongly on temperature and a sharper cut-off can be observed at relatively high-temperatures. This study is pertinent to the application of InAs/GaSb type II SLs as THz photodetectors. PACS numbers: 72.80.Cw, 72.20.Dp, 73.61.Cw