A comprehensive set of simulation tools to model and design high-performance Type-II InAs/GaSb superlattice infrared detectors

In this work, the electronic band structure of the InAs/GaSb superlattice (SL) is calculated using a commercial 8-band k⸳p solver and the electrical performance of longwave nBp device structure evaluated with Atlas from Silvaco software. By taking into account an InSb interface layer and the interface matrix (formulated by P.C. Klisptein), the model can predict the measured energy band gap of different InAs/GaSb SLs having different period composition and thickness (7/4, 10/4, 12/4, 14/4 and 14/7 SLs) within an error corresponding to the ±𝑘_𝐵𝑇 deviation range. The effective mass is then extracted from the electronic band structure calculation and discussed for numerous SL designs. In particular, we compare a 14/7 SL and a 12/2 SL having an energy band gap equal to 0.122 and 0.118 eV at 77K, respectively. The electron-hole wavefunction overlap for the 12/2 SL has been estimated to be ~74%, which is almost twice the value calculated for the 14/7 SL (~40%). This arises from the delocalization of carriers in a thinner SL period also leading to smaller carrier effective masses in the 12/2 SL. The dark-current of a nBp structure has been calculated for both SLs. For the 14/7 SL, the dark-current level has been found to be higher by a factor of over 3 than the Rule07 benchmark, whereas for the 12/2 SL, it is lower by a factor of 0.77, demonstrating that the SL design can be used to improve the device performances.