Planar Pb0.8Sn0.2Te photodiode array development at the night vision laboratory

Planar photodiode arrays sensitive to i.r. radiation of 11 μm wavelength when operating at 77°K have been fabricated by evaporating several hundred angstroms of indium onto bulk Pb0.8Sn0.2Te annealed to carrier concentrations of 1 2 × 1017 cm−3 and mobilities of 2 3 × 104 cm2 V−1 sec−1. This evaporation has been followed by a short thermal treatment involving temperatures between 100–200°C. Photodiodes formed by this process have had peak detectivities of 2 × 1010 cm Hz12 W−1 with junction area—zero bias resistance products of 0.8 Ω cm2 and quantum efficiencies of 45%. Device characteristics and fabrication details are presented.