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

•N-structure is a new design of barrier infrared detector.•The structure is based on InAs/AlSb/GaSb based type-II superlattice system.•HH–LH splitting energies are calculated for AlSb and InSb interfaces.•AlSb barriers perform enhanced e–h overlaps leading to higher detectivity.•Electrical and optical results are promissing for high temperature applications.

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 125 K were obtained as 1.8 × 10−6 A cm−2 and 800 Ω cm2 at zero bias, respectively. The specific detectivity was measured as 3 × 1012 Jones with cut-off wavelengths of 4.3 μm at 79 K reaching to 2 × 109 Jones and 4.5 μm at 255 K.