IR Scene Simulation Research Articles

HgCdTe negative luminescence devices for cold shielding and other applications

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 (λco=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.