InP-based GaAsSb/AlGaAsSb/T2SL barrier-type low-bias tunable dual-band NIR/eSWIR photodetectors

A bias-selectable near-infrared (NIR) and extended short wavelength infrared (eSWIR) dual-band bandgap engineered Ga_0.51As_0.49Sb/Al_0.85Ga_0.15AsSb/T2SL (In_0.53Ga_0.47 As/Ga_0.51As_0.49Sb) infrared photodetector, vertically stacked in a monolithic grown on InP substrate, is demonstrated. GaAsSb NIR sub-detector and T2SL eSWIR sub-detector are operated under small forward and reverse bias, respectively. The GaAsSb sub-detector functions within the NIR spectrum, with a 100% cutoff wavelength of 1.72 μm at 50 mV, achieving a peak responsivity of 0.560 A/W at 1.55 μm and a specific detectivity (D*) of 1.48 ×10¹¹ c m⋅H z ^1/2/W. At -250 mV, the T2SL eSWIR sub-detector functions in the eSWIR band, exhibiting a 100% cutoff wavelength of 2.6 μm. The peak responsivity is 0.273 A/W at 2.0 μm, with a specific detectivity of 6.11 ×10⁹ c m⋅H z ^1/2/W. The present work demonstrates the potential of the dual-band photodetector for multispectral SWIR applications.