Quantum dots of InAs/GaSb type II superlattice for infrared sensing

Throughout the past years, significant progress has been made in Type II (InAs/GaSb) photovoltaic detectors in both LWIR and VLWIR ranges. BLIP performance at 60 K for 16 μm photovoltaic type II detectors has been successfully demonstrated for the first time. The detectors had a 50% cut-off wavelength of 18.8 μm and a peak current responsivity of 4 A/W at 80 K. A peak detectivity of 4.5×10¹⁰cm·Hz^1/2/W was achieved at 80 K at a reverse bias of 110 mV. Detectors of cutoff wavelength up to 25 μm have been demonstrated at 77 K. The great performance of single element detectors appeals us to lower dimensional structures for both higher temperature performance and possible wavelength tunability. Simple calculations show that quantum effects will become significant when the lateral confinement is within tens of nanometers. The variation of applied gate voltage will move the electron and hole energy levels unevenly. The cutoff wavelength of the superlattice will vary accordingly. Auger recombination will also decrease and higher temperature operation becomes possible. In this talk, the latest results will be discussed.