As an alternative to mercury-cadmium telluride (MCT), this program will investigate the optical properties of a recently invented class of type II strained-layer superlattices made of (GA,As) related compounds. The new concept has advantages compared with previous efforts in that small band-gaps may be achieved with sufficiently thin repeating layers in the superlattices so that they have good optical absorption properties and favorable electrical transport properties original calculations have indicated Ga1-xInxSb/InAs to be the best choice for such application. Very recently it has been shown to have the highest absorption coefficient at 10um wavelength compared to all other superlattice materials. To explore the potential of this material system, the investigators will fabricate the detector device structures by a multi-process molecular beam epitaxy technique in which the detector layers, passivation and metallization are all done in-situ.
