Exploration of novel InSbBi alloy for uncooled infrared photodetector applications

In this paper, we report on the growth and investigation of InSbBi alloy for uncooled infrared photodetector applications. The epitaxial layers were grown on InSb and GaAs substrates by low pressure metalorganic chemical vapor deposition. The incorporation of Bi was verified by various techniques such as high resolution x-ray diffraction, energy dispersive x-ray analysis, and infrared photoresponse measurements. The maximum incorporation of Bi estimated from the optical band gap change was 5.8 %. Preliminary photoconductive detectors based on this material are reported. The responsivity of an InSb_0.96Bi_0.04 photodetector at 7 μm was about 3.2 V/W at 77 K with corresponding Johnson noise limited detectivity of 4.7 × 10⁸ cmHz^1/2/W. The carrier lifetime of an InSb_0.96Bi_0.04 detector was estimated to be about 86 ns from the voltage dependent responsivity measurements. Room temperature operating 8-12 μm InSb_0.95Bi_0.05 photodetector was also demonstrated. The voltage responsivity at 10.6 μm was about 1.9 mV/W at room temperature and the corresponding Johnson noise limited detectivity was estimated to be about 1.2×10⁶ cmHz^1/2/W.