Performance Comparison of Long-Wavelength Infrared Type II Superlattice Devices with HgCdTe

The InAs/GaSb family of type II superlattices (T2SL) is the only known infrared (IR) detector material having a theoretically predicted higher performance than HgCdTe. The Auger lifetime has been predicted to be much longer, offering the possibility of much lower dark currents. In this paper the present state of the technology for long-wavelength infrared (LWIR) applications is evaluated by examining the dark current density in LWIR T2SL diodes at 78 K as a function of device cutoff wavelength, and comparing it with the HgCdTe benchmark known as Rule 07. The dark current density remains greater than Rule 07, but it has rapidly decreased in recent years with advancing technology, particularly due to innovative barrier structures.