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Strained layer superlattices based on Sb semiconductor material are proposed for long wavelength photodetector applications. Theoretical studies on the band structure of AlGaSb/GaSb, AlInSb/InSb, and GaInSbfInAs superlattices showthat the wavelength coverage can be extended from 0.5 to 30 Optical absorptions of the superlattices are calculatedtaking into account the intermixing effect at different diffusion lengths. Responsivity and detectivity of the GaInSb/InAssuperlattice detector are also analyzed. Blue shift of responsivity is observed for increased intermixing and the detectivity D* at 77 K is increased by more than one fold in magnitude as RA increases linearly with intermixing.Keywords: Superlattice, Photodetector, Intermixing, Responsivity, Absorption, Detectivity 1. INTRODUCTION Great effort has been devoted to the development of near and far infrared photodetectors. Conventionally, most ofthe infrared detectors are based on the bulk Il-VT material such as mercury cadmium telluride (MCT)'. However, therequirement of extremely precise alloy composition control to accurately determine the band gap, large tunneling darkcurrents, and Auger recombination rates has limited the performance of MCT detectors for array applications. With theadvanced of epitaxy and growth technologies, heterostructures with abrupt interfaces and precise layer thickness areachievable. Small band gap semiconductor heterostructures based on Sb material has thus appeared as a candidate for longwavelength infrared detection. Sb-based superlattices express greater uniformity and low band-to-band tunneling2, as |
