Lead Telluride p-n Junctions for Infrared Detection: Electrical and Optical Characteristics

PbTe mesa diodes were fabricated from a series of p−n junctions grown on BaF2 substrates. For this series, the hole concentration was kept constant at 1017 cm−3 and the electron concentration varied between 1017 and 1019 cm−3. Capacitance versus voltage analysis revealed that for n > 1018 cm−3, a one-sided abrupt junction is formed. The direct and reverse branches of the current versus voltage curves exhibited different forms among the diodes. The R0A product varied between 0.23 and 31.8 Ωcm2, and the integral detectivity ranged from 1.1x108 to 6.5x1010 cmHz1/2W−1. The performance of the best PbTe photodiodes fabricated here is comparable to the commercial InSb and HgCdTe infrared detectors, and to the PbTe sensors grown on Si substrate.