Large hh-lh splitting energy for InAs/AlSb/GaSb based N-structure photodetectors

Abstract

We investigate the band properties of InAs/AlSb/GaSb (N-structure) and InAs/GaSb material based type II superlattice (T2SL) photodedectors. The superlattice empirical pseudopotential method is used to define band-structures such as the bandgap and heavy hole-light hole (hh-lh) splitting energies in the mid-wavelength infrared range (MWIR) and long wavelength range (LWIR). The calculations are carried out on the variation of AlSb/GaSb layer thickness for (InAs)(10.5)/(AlSb)(x)/(GaSb)(9-x) and the variation of InAs layer thickness for (InAs)(x)/(AlSb)(3)/(GaSb)(6) T2SL structures at 77 K. For the same bandgap energy of 229 meV (5.4 mu m in wavelength), hh-lh splitting energy is calculated as 194 meV for the (InAs)(7.5)/(AlSb)(3)/(GaSb)(6) structure compared to the (InAs)(10.5)/(GaSb)(9) structure with hh-lh splitting energy of 91 meV within the MWIR. Long wavelength performance of InAs/AlSb/GaSb structure shows superior electronic properties over the standard InAs/GaSb T2SL structure with larger hh-lh splitting energy which is larger than the bandgap energy. The best result is obtained for (InAs)(17)/(AlSb)(3)/(GaSb)(6) with the minimum bandgap of 128 meV with hh-lh splitting energy of 194 meV, which is important for suppressing the Auger recombination process. These values are very promising for a photodetector design in both MWIR and LWIR in high temperature applications. Published by AIP Publishing.