N-structure based on InAs/AlSb/GaSb superlattice photodetectors

Abstract

We have studied the theoretical and experimental properties of InAs/AlSb/GaSb based type-II superlattice (T2SL) pin photodetector called N-structure. Electronic properties of the superlattice such as HH–LH splitting energies was investigated using first principles calculations taking into account InSb and AlAs as possible interface transition alloys between AlSb/InAs layers and individual layer thicknesses of GaSb and InAs. T2SL N-structure was optimized to operate as a MWIR detector based on these theoretical approaches tailoring the band gap and HH–LH splitting energies with InSb transition layers between InAs/AlSb interfaces. Experimental results show that AlSb layers in the structure act as carrier blocking barriers reducing the dark current. Dark current density and R0A product at 125K were obtained as 1.8×10−6Acm−2 and 800Ωcm2 at zero bias, respectively. The specific detectivity was measured as 3×1012Jones with cut-off wavelengths of 4.3μm at 79K reaching to 2×109Jones and 4.5μm at 255K.