15 October 2012 Annealing effect on the long wavelength infrared InAs/GaSb superlattice materials
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Abstract
Annealing effect on the quality of long wavelength infrared (LWIR) InAs/GaSb superlattices (SLs) has been investigated using atomic force microscopy (AFM), photoconductivity, temperature dependent Hall, and time-resolved differential transmission measurements using an electronically delayed pump-probe technique. Quarters of a single SL wafer were annealed at 440, 480, and 515 °C, respectively for 30 minutes under a Sb-over pressure. Morphological qualities of the SL surface observed by AFM did not show any indication of improvement with annealing. However, the spectral intensity measured by photoconductivity showed an approximately 25 % improvement, while the band gap energy remained at ~107 meV for each anneal, The electron mobility was nearly unaffected by the 440 and 480 °C anneals, however showed the improvement with the 515°C anneal, where the mobility increased from ~4500 to 6300 cm2/Vs. The minority carrier lifetime measured at 77 K also showed the improvement with annealing, increasing from 12.0 to 15.4 nanoseconds. In addition to the longer lifetimes, the annealed samples had a larger radiative decay component than that of unannealed sample. Both the longer measured lifetime and the larger radiative decay component are consistent with the modest improvement in the quality of the annealed SL sample. Overall the qualities of LWIR SL materials can be benefit from a post growth annealing technique we applied.
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H. J. Haugan, G. J. Brown, S. Elhamri, B. V. Olson, T. F. Boggess, L. Grazulis, S. Pacley, "Annealing effect on the long wavelength infrared InAs/GaSb superlattice materials", Proc. SPIE 8512, Infrared Sensors, Devices, and Applications II, 85120K (15 October 2012); doi: 10.1117/12.928713; https://doi.org/10.1117/12.928713
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