, Volume 35, Issue 6, pp 1391-1398

HgCdTe negative luminescence devices for cold shielding and other applications

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Negative luminescence (NL) refers to the suppression of infrared blackbody emission, and hence an apparent temperature reduction, due to free carrier extraction from a reverse-biased p-n junction. A number of applications are envisioned for NL devices, including cold shielding of background-limited uncooled and cryogenic focal-plane arrays, dynamic nonuniformity correction for ir imaging, and ir scene simulation. High-performance NL devices have recently been demonstrated. For example, a HgCdTe/CdZnTe photodiode with 4.8-µm cutoff wavelength achieved an internal NL efficiency of 95% at room temperature. This means that the blackbody emission was suppressed by a factor of 20 and that the apparent temperature of the device surface decreased by 60 K. The corresponding reverse-bias saturation current density was 0.11 A/cm2. Even HgCdTe devices (λ co=5.3 µm) grown on large-area silicon substrates with substantial lattice mismatch displayed 88% internal NL efficiency and saturation current densities no larger than 1.3 A/cm2. These results indicate a clear path toward a negative-luminescence device technology that is efficient, operates at low power, and is inexpensive.