Long-Period InAs/GaSb Type-II Superlattices for Terahertz Application

We present a theoretical study on the terahertz (THz) optoelectronic properties of long-period InAs/GaSb type-II super lattices (SLs). The eight-band k·p model is used to calculate the electronic structures of such SLs and on the basis of band structures, the Boltzmann equation approach is employed to calculate the optical absorption coefficients for the corresponding SL systems. It is found that long-period InAs/GaSb type-II SLs have a considerable absorption in the THz bandwidth. By examining the dependence of THz absorption coefficient on the InAs/GaSb layer widths, we demonstrate that with a proper choice of InAs/GaSb layer widths, an optimized THz absorption can be achieved. This study is pertinent to the potential application of InAs/GaSb type-II SLs as THz photo detectors.