Planar Engineering for Type-II Superlattices (PETS

Type II InAs/GaSb strained layer superlattices (SLS) represent the most promising material system capable of delivering more producible, large-format MWIR and LWIR focal plane arrays (FPAs). Type-II SLS currently achieve performance comparable to that of existing mercury-cadmium-telluride (MCT) based FPAs. However, no viable planar processing techniques have been demonstrated for Type-II ¡V they currently rely on mesa isolated diodes. These mesas require etching, cleaning, and passivation, which complicate the processing of Type-II SLS and can decrease the yield and reliability. As such it is desirable to pursue a planar processing technique that is compatible with Type-II superlattices. In this proposal we present a novel planar design compatible with Type-II design called Planar Engineering for Type-II Superlatices (PETS). PETS consists of a reduced area p-type GaSb layer that is fabricated via selective area re-growth in a trench in a ƒÞ-type (lightly n-type) absorbing layer. This eliminates the need to passivate the devices and simplifies the processing, and thus can be expected to increase the yield and reliability leading to a more producible FPA. In addition PETS allows for a reduced junction area while maintaining the optical area of the device. This will reduce the dark current and lead to higher signal to noise ratios.