InAs/InGaSb type-II superlattices have advantages over HgCdTe for photodetectors requiring higher temperature and longer wavelength operation. The type-II QW photodiodes have comparable quantum efficiency, smaller dark current due to a larger effective mass, much slower Auger recombination rates, and hence much longer carrier lifetimes. Through careful bandgapengineering, we have suppressed the Auger coefficient by a factor of >8 for 4.5 -um type-II lasers at 300 K. In the phase-I program, we have demonstrated many high-performance photoconductors directly grown on compliant GaAs substrates with a cutoff wavelength from 11 um to 19 um. We have also demonstrated and dramatically improved the quality of 2-inch compliant GaAs substrates. With the improvement of materials growth and compliant substrates, more than a factor of 1500 of improvement has been achieved in the photoresponse. Further investigations will be performed to optimize the compliant substrates. Additionally, the coherent tunneling at the mesa-surface is the performance pitfall for ungated SLs mesa devices. To solve this issue, we propose to develop the surface passivation technology using sulfide materials to eliminate the side-wall leakage current. Therefore, we will be able to demonstrate large photodiode arrays with a detectivity >5x1012 cmHz 0.5/W at a wavelength of 14, um at 55 K. Critical military needs include missile defense, remote chemical sensing for defense against biological/chemical warfare, and medical. Commercial markets include leak detection, chemical process control, remote chemical sensing for atmospheric pollution and drug monitoring, IR spectroscopy, and medical diagnoses. With the development of high-performance photodectors, this program should considerably accelerate the commercialization of mid-IR photodetectors to meet the potential needs of the huge defense and commercial market
Keywords: Photodector, Compliant Substrate, Type - Ii Superlattice,Inas/Ingasb, Auger Recombination, Petecti
