High-Detectivity Very-Long-Wavelength Strain-Compensated Type II Superlattice Infrared Photo Detectors

Very-long-wavelength infrared (VLWIR) photo detectors are needed for infrared-based chemical identification and terrestrial mapping applications associated with the detection of weapons of mass destruction. This project will develop a material system for a high-performance type-II VLWIR photo detector fabricated on a GaSb substrate. The approach will involve (1) a strain-compensated type II superlattice structure, (2) a dark-current suppression technique for InAs/GaSb/AlGaSb superlattice PIN diodes in the depletion region, and (3) an atomic-hydrogen-enhanced growth and surface preparation technique. Phase I will characterize the positive affects of strain-compensation and dark current suppression process in type II PIN structures. Phase II will refine the techniques to realize type II superlattice detectors in the 300-1000 cm-1 region at liquid nitrogen temperatures. Commercial Applications and other Benefits as described by the awardee The technology should result in higher optical absorption, higher operating temperature, higher material purity, and very low dislocation density, factors that should significantly enhance device operation in the 300-1000 cm-1 region. Photo detector arrays using this material would be of great interest to the DOE for various applications, including, in particular, imaging and remote sensing.