Type II InAs/GaSb Superlattices on GaAs for Infrared Photodetectors

Cheaper and higher performance infrared detectors in the mid and long wavelength infrared (MWIR and LWIR) spectral bands are needed for next generation ballistic missile defense programs. Type II InAs/GaSb superlattices represent the most promising material system capable of delivering a more affordable and producible focal plane array (FPA) technology than the current technology, while at the same time exhibiting similar or better performance. Two of the major challenges in the realization of FPA in this system pertain to the unintentionally doped p-type GaSb substrate used in the growth of type II superlattices: its strong infrared absorption and its thermal mismatch with the ROIC that leads to cracking upon hybridization and thus limits the FPA size. It is here proposed to demonstrate a prototype single element superlattice photodetectors and pixel arrays on more robust and optically transparent (in the infrared spectral bands of interest) GaAs substrates.