Strong terahertz absorption in long-period InAs/GaSb type-II superlattices with inverted band structures

• There is a significant electron–hole hybridization in inverted InAs/GaSb SLs.
• The electron–hole hybridization causes a very strong THz absorption in such SLs.
• The absorption features are well manifested by electron–hole hybridization degree.
• The strong THz absorption can be further improved and optimized by InAs/GaSb widths.

We present a theoretical investigation on the terahertz (THz) absorption by long-period InAs/GaSb type-II superlattices (SLs) with inverted band structures. It is found that in such SLs the band inversion causes a significant electron–hole hybridization and a strong THz absorption can be induced by this hybridization. The THz absorption coefficient is even larger than mid-infrared absorption coefficient for short-period InAs/GaSb SLs. Moreover, we find that the strong THz absorption can be further improved and optimized by the proper choice of InAs/GaSb layer widths. The interesting absorption features are well manifested in hybridization gaps and optical transition matrix elements. This study is pertinent to the potential application of long-period inverted InAs/GaSb type-II SLs as high-efficiency THz photodetectors.