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Two different effects of annealing, 1) on the arsenic activation in the in-situ doped mercury cadmium telluride (HgCdTe) layers grown on silicon substrates by molecular beam epitaxy (MBE) and 2) on the CdTe passivant-HgCdTe interface leading to significant changes in the characteristics of metal-insulator-HgCdTe (MIS) and planar photovoltaic (PV) detectors are discussed here. On the arsenic activation, highly compensated n-type properties to 100 percent activation of arsenic up to a total arsenic concentration of 1-2 X 1018 cm-3 and a decrease in activation thereafter are observed for annealing temperatures in the range of 235 to 450 degrees C. A range of annealing effects varying from unidentified structural defects acting as donors, probably due to donor arsenic tetramers or donor tetramers or donor tetramer clusters at 235 degrees C, to dissociation of bonds of neutral arsenic tetramer clusters to enable arsenic to occupy Te sites and behave as acceptors at 450 degrees C, are invoked to explain the arsenic activation mechanisms. The activation annealing, on the other hand, was found to have detrimental effect on the passivant-HgCdTe interface, possibility due to mercury diffusion during post-implant annealing. Capacitance-Voltage of MIS devices and current-voltage characteristics of planar diodes show tunneling limited performance with in-situ grown CdTe after annealing and show dramatic improvement in the performance characteristics when the in-situ grown CdTe is chemically removed and fresh CdTe passivation layer grown by MBE after arsenic activation annealing. Test structures containing mini arrays of square diodes with variable areas from 5.76 X 10-6 cm2 to 2.5 X 10-3 cm2 and MIS devices are used to establish the aforementioned effect. Under optimized conditions, state-of- the-art performance of the diodes in the mid-wavelength IR region with dynamic impedance on the order of 107 Ohm- cm2 is demonstrated.
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