Negative luminescence from MWIR HgCdTe/Si devices

The negative luminescence (NL) of a midwave-infrared (MWIR) HgCdTe photodiode (λ_co = 5.3 μm at 295 K) was investigated using both a modulated, self-referencing, optical technique and an electrical modulation technique. The internal negative luminescence efficiencies measured using optical modulation were 88% throughout the 3-5 μm spectral region, and nearly independent of temperature in the 240-300 K range. This corresponds to an apparent temperature reduction of 53 K at room temperature and 35 K at 240 K when a saturation reverse bias is applied. Efficiencies measured by the electrical modulation technique were consistent with the measured internal efficiencies and the measured reflectivity of the device. The reflectance and emission spectra measured with an FTIR spectrometer were modelled using empirical HgCdTe absorption formulas. The reverse saturation current density of 1.3 A/cm² is lower than any reported previously in the literature for an NL device with cut-off wavelength beyond 4 μm.