Develop and Demonstrate High Performance Infrared Focal Plane Arrays with Advanced Quantum Structures

In contrast to conventional type-I multiple quantum wells or superlattices (SL), the interband optical transition in type-II superlattices (T2SL) is spatially indirect. Therefore, its effective bandgap can be narrower than that of any of the single constituent materials. In general, there are two categories of type-II alignments for heterostructures, broken-gap alignment and staggered alignment (see Fig. 1). Such a unique property of T2SL has made it a good candidate for infrared photodetector applications. Significant progress has been made recently in the research on long-wavelength IR InAs/InGaSb T2SLs. These IR detector materials have potential to outperform existing materials such as HgCdTe and InSb. In the past several years, impressive achievements have been demonstrated by several research groups in the US with strong support from MDA. This effort proposes to improve on the state of the art InAs/InAsSb strained layer superlattice devices with better interface characteristics, better reproducibility, and better carrier transport than existing technologies.