MWIR and LWIR HgCdTe Infrared Detectors Operated with Reduced Cooling Requirements
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In this work, we analyze Auger suppression in HgCdTe alloy-based device structures and determine the operation temperature improvements expected when Auger suppression occurs. We identified critical material (absorber dopant concentration and minority-carrier lifetime) requirements that must be satisfied for optimal performance characteristics. Calculated detectivity values of Auger-suppressed and standard double-layer planar heterostructure (DLPH) devices demonstrate consistently higher maximum background-limited temperatures over a range of cutoff wavelengths and generally higher detectivity values achieved by Auger-suppressed detectors. Furthermore, these devices can operate with comparable performance at up to 100 K higher than DLPH detectors operating at reference temperatures above 100 K. Results of these simulations demonstrate that Auger-suppressed detectors provide a significant advantage over DLPH devices for high-temperature operation and are a viable candidate for thermoelectrically cooled detectors. Experimental dark current–voltage (I–V) characteristics between 120 K and 300 K were fitted using numerical simulations. By fitting the temperature-dependent I–V experimental data, we determined that the observed negative differential resistance (NDR) is due to Auger suppression. More specifically, NDR is attributed to full suppression of Auger-1 processes and partial (~70%) suppression of Auger-7 processes. After Auger suppression, the remaining leakage current is principally limited by the Shockley–Read–Hall recombination component. Part of the leakage current is also due to a residual Auger-7 current in the absorber due to the extrinsic p-type doping level. Analysis and comparison of our theoretical and experimental device results in structures where Auger suppression was realized are also presented.
KeywordsHgCdTe infrared detectors high operating temperature Auger suppression lifetime molecular-beam epitaxy negative differential resistance minority-carrier lifetime
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We are grateful for support from the U.S. Army under SBIR Contract W911QX-08-C-0106.