ABSTRACT
The InAs/GaSb superlattice infrared detector has been developed with tremendous effort. However, the performance of it, especially long-wavelength infrared detectors (LWIR), is still limited by the electrical performance and optical quantum efficiency (QE). Forcing the active region to be p-type through proper doping can highly improve QE, and the gating technique can be employed to greatly enhance electrical performance. However, the saturation bias voltage is too high. Reducing the saturation bias voltage has broad prospects for the future application of gate voltage control devices. In this paper, we report that the gated P+-π-M-N+ InAs/GaSb superlattice long-wavelength infrared detectors exhibit different π region doping levels that have a reduced minimum saturation bias at - 10 V with a 200-nm SiO2 layer after a simple and effective anodic vulcanization pretreatment. The saturation gate bias voltage is much lower than - 40 V that reported with the same thickness of a 200-nm SiO2 passivation layer and similar structure. The optical and electrical characterization indicates that the electrical and optical performance of the device would be weakened by excessive doping concentration. At 77 K, the 50% cutoff wavelength of the device is about 8 µm, the 100% cutoff wavelength is 10 µm, the maximum quantum efficiency is 62.4%, the maximum of responsivity is 2.26 A/W at 5 µm, and the maximum RA of the device is 1259.4 Ω cm2. Besides, the specific detectivity of Be 780 °C-doped detector without gate electrode exhibits a peak of 5.6 × 1010 cm Hz1/2/W at 5 µm with a 70-mv reverse bias voltage, which is more than three times that of Be 820 °C-doped detector. Moreover, the peak specific detectivity could be further increased to 1.3 × 1011 cm Hz1/2/W at 5 µm with a 10-mv reserve bias voltage that has the bias of - 10 V at the gate electrode.
