PLANAR Pb0·8Sn0·2Te PHOTODIODE ARRAY DEVELOPMENT AT THE NIGHT VISION LABORATORY

Abstract Planar photodiode arrays sensitive to i.r. radiation of 11 μ m wavelength when operating at 77°K have been fabricated by evaporating several hundred angstroms of indium onto bulk Pb 0·8 Sn 0·2 Te annealed to carrier concentrations of 1 2 × 10 1- cm 3 and mobilities of 2 3 × 10 4 cm 2 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 × 10 10 cm Hz 1/2 W -1 with junction area—zero bias resistance products of 0·8 ω cm 2 and quantum efficiencies of 45%. Device characteristics and fabrication details are presented.