Physics and technology of antimonide heterostructure devices at SCD

SCD has developed a range of advanced infrared detectors based on III-V semiconductor heterostructures, grown on GaSb. The XBn/XBp family of detectors enables diffusion limited behavior with dark currents comparable with MCT Rule-07 and with high quantum efficiencies. InAsSb/AlSbAs based XBn focal plane array detectors with a cut-off wavelength of ∼ 4.1 μm and formats presently up to 1024×1280 / 15 μm, operate with background limited performance up to ∼175 K at F/3. They have a sensitivity and image quality comparable with those of standard InSb detectors working at 77K. In an XBp configuration, the same concept has been applied to an InAs/GaSb type II superlattice (T2SL) detector with a cut-off wavelength of ∼ 9.5 μm, which operates with background limited performance up to ∼100 K at F/2. In order to design our detectors effectively, a suite of simulation algorithms was developed based on the k<. p and optical transfer matrix methods. In a given T2SL detector, the complete spectral response curve can be predicted essentially from a knowledge of the InAs and GaSb layer widths in a single period of the superlattice. Gallium free T2SL detectors in which the GaSb layer is replaced with InAs_1-xSb_x (x ∼ 0.15-0.5) have also been simulated and the predicted spectral response compared for the two detector types.