Research Activity on Type II InAs/GaSb Superlattice for LWIR Detection and Imaging at the Center for Quantum Devices.

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Type II superlattice photodetectors have recently experienced significant improvements in both theoretical structure design and experimental realization. Empirical Tight Binding Method was initiated and developed for Type II superlattice. A new Type II structure, called M-structure, was introduced and theoretically demonstrated high RoA, high quantum efficiency. Device design and growth condition were optimized to improve the performance. As a result, a 54% quantum efficiency, a 12 Ohm.cm² RoA were achieved for 11 µm cut-off photodetector at 77 K. Effective surface passivation techniques for MWIR and LWIR Type II superlattice were developed. FPA imaging at MWIR and LWIR were demonstrated with a capability of imaging up to room temperature and 211 K respectively. The noise equivalent temperature difference presented a peak at 50 mK for MWIR FPA at 121 K and 26 mK for LWIR FPA at 81 K. ©2007 American Institute of Physics