High-operating temperature MWIR unipolar barrier photodetectors based on strained layer superlattices

The realization of high operating temperature (HOT) midwave infrared (MWIR) photodetectors would significantly relax the requirements imposed on the cooling system, which would lead to a reduction in the size, weight, and cost of the detection system. One of the most attractive material systems to develop HOT photodetectors is InAs/GaSb Type II Superlattice (T2SL). This is due the ability of T2SL materials to engineer the band structure of the device, which can be exploited to make devices with unipolar barriers. It has been shown that the use of unipolar barriers can dramatically reduce the dark current levels of the device, which is essential to realize HOT photodetectors. In this work, we report on the performance of a unipolar barrier mid wave infrared detector based on type-II InAs/GaSb strained layer superlattice for high operating temperatures. The device architecture is the double-barrier heterostructure, pBiBn design. Under an applied bias of -10 mV and an operating temperature of 200 K, the best performing devices show a dark current density of 4.9×10^-4 A/cm². At 200 K, the measured zero-bias specific detectivity was 4.4×10¹⁰ Jones.