Passivation of Type II Superlattices for VLWIR Sensors

Very long wavelength infrared (VLWIR) detectors are highly needed for midcourse phase missile defense. Blocked impurity band detectors are capable of sensing at these wavelengths but require extremely low temperatures, in the 10K or less range. The InAs/GaSb Type II heterostructure system offers unique design flexibility for new innovative detectors. By incorporating dark current reduction techniques, we can provide the basis for 77K detection in the 15-25 micrometer spectral range. Several tasks are required to address the application of Type II superlattices for VLWIR sensors: (i) Design of a suitable structure with cutoff wavelength in the VLWIR at the desired operating temperature (ii) Optimization of the epitaxial growth conditions for VLWIR superlattice material with the goal of minimizing recombination centers, and (iii) Development of processes for uniform and reproducible sidewall passivation.