The design of single-crystal infra-red photocells

Explicit formulae are given for the sensitivity of single-crystal photocells used as photo-conductive, photo-electromagnetic and p-n junction detectors. The equivalent noise input can be expressed as the product of functions depending on the bulk and surface properties respectively. The parameters governing the design of photocells of high sensitivity are discussed, and the results are applied to the semiconductors indium antimonide, indium arsenide and lead sulphide. It is shown that the best mode of operation for a semiconductor may be inferred from the carrier mobility, lifetime and surface recombination velocity.