HgCdTe Negative Luminescence Devices for Cold Shielding and Other Applications

摘要

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-mu m 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/cm~2.Even HgCdTe devices(lambda_(co)=5.3 mu m)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/cm~2.These results indicate a clear path toward a negative-luminescence device technology that is efficient,operates at low power,and is inexpensive.