Investigation of the surface leakage current of the nBn InGaAsSb infrared photodetector by using photoreflectance spectroscopy

•The nbn infrared detectors suppress the dark current and surface leakage current.•Unipolar barrier limits the flow of electrons to the surface.•Generation–Recombination is eliminate at low temperature.•Electric field varied low at low temperature because of low surface leakage.•Electric field was analysed by using the Photoreflectance spectroscopy.