Progress on MBE Grown Type-II Superlattice Photodiodes

摘要

The closely lattice-matched material system of InAs, GaSb, and AlSb, commonly referred to as the 6.1 A material system, has emerged as a fertile ground for the development of new solid-state devices. The flexibility of the system in simultaneously permitting type-I, type-II staggered, and type-II broken-gap band alignments has been the basis for many novel, high-performance heterostructure devices in recent years, including the GaInSb/InAs type-II strained layer superlattice infrared detectors proposed by Smith and Mailhiot in 1987. The type-II superlattice design promises optical properties comparable to HgCdTe, better uniformity, reduced tunneling currents, suppressed Auger recombination, and normal incidence operation. In 1990, Chow and co-workers first reported Ga{sub}(1-x)In{sub}xSb/InAs superlattice materials with high structural quality, LWIR photoresponse, and LWIR photoluminescence. Later, researchers demonstrated excellent detectivity (approaching HgCdTe, 8-μm cutoff, 77K) on individual superlattice devices. Currently, superlattice detector technology is undergoing the transition from single element detectors into high-performance focal plane imaging arrays.