Investigation of indium arsenide antimonide material system for uncooled long-wavelength infrared photodetector applications

Infrared detectors operating in the 8 to 14 μm atmospheric window are of great importance in various military, industrial, and civilian applications. Minimization of cooling requirements is also another important factor because cooling equipment add considerable amount to the system cost. To achieve infrared detection at high temperature, thermal detectors have been developed and are currently in use. However, their detectivity is low especially at high frequencies. To achieve high sensitivity and fast response, photon detectors based on semiconductors have been studied. Early research effort has been carried out on the pre-established material system, mercury cadmium telluride (HgCdTe). However, HgCdTe suffers from various lattice, surface, and interface instability problems caused by weak ionic bonding and high Hg vapor pressure.; As an alternative, InAsSb alloys have been investigated in this study because it can cover the 8 to 14 μm range at room temperature. Being a III–V compound, InAsSb benefits from superior bond strengths and material stability, well-behaved dopants, and high quality substrates. Thus, InAsSb is a good candidate for the uncooled photodetector applications. The difficulties in growth have been overcome by advanced growth technology, metalorganic chemical vapor deposition (MOCVD). The material characteristics have been studied in detail. Device modeling was also performed in both analytical and numerical ways to optimize the detector structures. Both photoconductive and photovoltaic detectors were demonstrated on GaAs substrates. The first room temperature photoresponse up to 13 μm by any III–V semiconductors were obtained from these detectors with John noise limited detectivity of $\sim 3\times 107$ cmHz1/2/W. These results showed the feasibility of InAsSb photodetectors to replace the current thermal and HgCdTe uncooled detectors.; In summary, InAsSb is an excellent candidate to replace the current material systems used for uncooled infrared detectors. The first uncooled InAsSb photodetectors operating up to 13 μm have been demonstrated. Thus the results of these experiments will have direct technological importance by providing the experimental growth, characterization, device modeling, and device fabrication guidelines as well as a basic understanding of detector performance for the InAsSb material system.