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

摘要

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 R_0A product at 125 K were obtained as 1.8 × 10~(-6)A cm~(-2) and 800 Ω cm~2 at zero bias, respectively. The specific detectivity was measured as 3 × 10~(12) Jones with cut-off wavelengths of 4.3 μm at 79 K reaching to 2 × 10~9 Jones and 4.5 μm at 255 K.