Photodetection properties of Cu2Se-AgInSe2 heterojunctions

Abstract

Heterojunctions were formed by vacuum evaporation of p-type Cu2Se on n-type AgInSe2 substrates. The photodetection characteristics of these diodes are vastly improved over those previously reported. At λ=1.05 μm, the room-temperature quantum efficiency approaches the reflection-limited value (∼0.7) as compared to ∼0.2 previously reported. In addition, the efficiency of the present diodes becomes greater than unity at low reverse biases. At 77 °K, even more dramatic gains can be achieved at low reverse biases. The structure appears to operate as an optically activated switch and is interpreted as a combination of photovoltaic and photoconductive mechanisms.