Strained Layer Superlattice Using HgTe for VLWIR Detection

Despite considerable progress with bulk HgCdTe photovoltaic technology, difficulties persist in sensing wavelengths longer than 12 microns with bulk alloy material due to the limitations imposed by high Auger recombination rates and large tunneling dark currents. Strained layer superlattices using HgTe layers and lattice mismatched layers based on ZnTe alloys are an extremely promising alternative for infrared systems requiring higher-temperature and longer-wavelength operation. In this type of superlattice, the active region layers are strained, thereby suppressing Auger recombination and thus allowing infrared sensing devices to be operated at temperatures above current standards. Moreover, the strain simultaneously suppresses tunneling currents. This SBIR program focuses on the development of buffer layers for the growth of VLWIR strained-layer superlattices, the growth and characterization of such superlattices and the fabrication and characterization of infrared detectors based on these materials.