The Growth of InAs/GaSb Type II Superlattices on Si Substrates for Infrared FPAs

High performance infrared detectors in the mid and long wavelength infrared (MWIR and LWIR) spectral bands are highly needed in a number of missile defense missions. 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 silicon ROIC that leads to cracking and thus limits the FPA size. It is therefore proposed here to study the feasibility of growing type II InAs/GaSb superlattices on silicon substrates in spite of a lattice mismatch of ~11 %. The design and optimization of an appropriate buffer layer technique will be an essential part of the proposed work.