Novel Sb-based alloys for uncooled infrared photodetector applications

We report on the growth and characterization of InSbBi, InTlSb, InTlP, and the quaternary alloys for uncooled longwavelength infrared photodetector applications. The layers were grown on InSb and GaAs substrates by low-pressure metalorganic chemical vapor deposition. The incorporation of Bi and Tl in InSb was investigated with high-resolution x-ray diffraction, energy dispersive x-ray analysis, and optical photoresponse measurements. We also demonstrate the photodetectors fabricated from the grown InSbBi and InTlSb alloys. InSb_0.96Bi_0.04 photoconductive detectors exhibited a responsivity of 3.2 V/W at 77 K. The estimated Johnson noise limited detectivity at 7 μm was 1.7×10⁸ cmHz^1/2/W at 7 A room temperature operating InSb_0.95Bi_0.05 photodetector was also demonstrated. Photoresponse up to 12 μm was achieved at 300 K. The responsivity and Johnson noise-limited detectivity at 10.6 μm were 1.9 mV/W and 1.2×10⁶ cmHz^1/2/W, respectively. Photoresponse up to 15 μm was achieved at 300 K from quaternary InTlAsSb and InBiAsSb alloys.