The over-saturation phenomenon of a Hg_0.46Cd_0.54Te photovoltaic detector irradiated by a CW laser

A Hg0.46Cd0.54Te (~0.91 eV bandgap) photovoltaic detector is exposed to 10.6 ?m and 1319 nm intense laser radiations. The open-circle voltage (Voc) of the detector is measured and found to decrease with laser power density above the saturation threshold. The characteristics of over-saturation phenomena are quite sensitive to the temperature. For the Hg0.46Cd0.54Te detector, the photon energy of a 10.6 ?m laser (sub-bandgap laser) is less than the bandgap, and the photon energy of a 1319 nm laser (above-bandgap laser) is above the bandgap. Both lasers can induce an over-saturation phenomenon, but the dominant mechanism is different. The results indicate that photovoltage and thermoelectric voltage are the dominant mechanisms for above-bandgap illumination, and thermovoltage and thermoelectric voltage are the dominant mechanisms for sub-bandgap illumination.