<title>Novel InTlSb and InSbBi alloys for uncooled photodetector applications</title>

Abstract

We report on the growth and investigation of InTlSb and InSbBi alloys for uncooled IR photodetector applications. The epitaxial layers of the materials have been grown on (100) InSb or GaAs substrates by low pressure metalorganic chemical vapor deposition. The incorporation of Tl and Bi has been verified by x-ray diffraction spectra, Auger electron spectroscopy, and energy dispersive x-ray analysis. The maximum incorporation of Tl and Bi estimated from the optical band gap change was 5.6 and 5.8 percent, respectively. The lattice contraction with the incorporation of Tl and Bi was verified by high resolution x-ray diffraction spectra. Tetragonal structure for the InSbBi and hybridized nature for the InTlSb alloys have been suggested to explain this abnormal behavior. The fabrication and characterization of photoconductive detectors based on these material are also reported. Photoresponse of InTlSb photodetectors was observed up to 11 micrometers at 300 K. The maximum responsivity of an In0.96Tl0.04Sb photodetector was about 6.6 V/W at 77K, corresponding to a Johnson noise limited detectivity of 7.6 X 108 cmHz1/2/W. The carrier lifetime in InTlSb photodetectors was 10-50 ns at 77K. The responsivity of the InSb0.96Bi0.04 photodetector at 7 micrometers was about 3.2 V/W at 77K with corresponding Johnson noise limited detectivity of 4.7 X 108 cmHz1/2/W. The carrier lifetime of InSbBi detector was estimated to be about 86 ns from the voltage dependent responsivity measurements. The InSb0.95Bi0.05 photodetectors exhibited peak responsivity of 7.0 X 10-3 V/W with photoresponse up to 12 micrometers and estimated carrier lifetime of 17 ns at room temperature.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.