Development of high-operation-temperature (up to 150 K) mid-wave infrared photodetectors based on p-n junctions in PbTe single crystals

One of the characteristic features of PbTe is an uncommon growth of bandgap with increasing temperature, which is quite opposite to the bandgap behavior of the semiconductors commonly used in electronics, for example, Si, Ge, GaAs, and InSb. This specificity allows one to increase the operating temperature of photodiodes fabricated using PbTe up to about 150 K. At the first stage of development, we prepared infrared (IR) photodiodes on the base of bulk single crystalline PbTe. To this end, the ingots with a diameter of about 40 mm were grown by the Czochralski technique. Then, the PbTe p-n junctions were fabricated by using indium donor diffusion to diffuse indium into the PbTe samples. Current-voltage and capacitance-voltage characteristics and spectral detectivity were measured over a wide temperature range and analyzed. The dark saturation current density at T = 100 K was of the order of 10⁻⁷ A/cm². Finally, the unique solid-state multi-stage thermoelectric cooler operated at temperatures up to 150 K was developed. The present study would pave the way to creating a module for efficient photodetection in the mid-wave IR range combining two solid-state devices, namely, the p-n photodiode and thermoelectric cooler, while the latter supports the former.