Strategy for the design of a non-cryogenic quantum infrared detector

A study of the optimization of the detectivity of a mid-infrared double heterostructure photovoltaic detector is proposed. Simple approximate analytic expressions for the dark current are compared with full numerical calculations, and give physical insight into the mechanisms dominating the dark current. The analysis is performed step by step in different structures, from a simple p–n junction to the full double heterostructure. The influence of temperature, barrier band gap energy in a double heterostructure and doping density in the active region, on diffusion and generation–recombination mechanisms is analysed. It is finally shown how the performances of a double heterostructure photovoltaic detector can be improved by a controlled doping of the active region, especially at low temperature.