Dual-Band Focal Plane Arrays with Double Unipolar Barrier InAs/GaSb Superlattices

In the proposed effort, SK Infrared LLC, a spin-off from the Krishna INfrared Detector (KIND) laboratory at the University of New Mexico (www.chtm.unm.edu/kind), in collaboration with Raytheon Vision Systems (RVS) is proposing to develop a dual band based imager using a novel unipolar heterostructure design with Type II InAs/GaSb strained layer superlattice detectors. The dual bands that are chosen for this application are midwave infrared (MWIR, 3-5 & #61549;m) and the long wave infrared (LWIR, 8-14 & #61549;m). However, these devices can be designed for different wavelength bands to suit the application needs of the customer. The dual band detectors will be developed using a novel double unipolar barrier design called"PbIbN". The advantage of the 6.1 family of semiconductors (InAs, GaSb and AlSb) is that it provides the device designer tremendous flexibility to control the valence band and conduction band offsets between the absorber and the barrier layers. The PbIbN device that will be investigated as a part of this proposal utilizes an electron barrier at the PI interface and a hole barrier at the IN interface. The unipolar barriers prevent the diffusion of minority carriers from either side of the absorber. Moreover, since the field drop is lower across the absorber region, the generation-recombination (GR) and tunneling currents are also reduced. The goal of the Phase I effort will be to demonstrate a single pixel PbIbN detector with dual band (MWIR/LWIR) operation with temporally simultaneous and spatially collocated detection. The Phase I option effort will transition this to an 8x8 array bonded to a fanout to determine the uniformity and reproducibility of the back-side illuminated devices. The Phase II effort will involve the demonstration of a 512x512 focal plane array in collaboration with RVS and their insertion into the Ballistic Missile Defense System (BMDS).