Equivalent circuit and fundamental limit of multi-stage infrared photodetectors

Based on an equivalent circuit model, a signal current in a multi-stage infrared (IR) photodetector is derived and used to discover a meaningful relation among quantum efficiency, collection efficiency, and particle conversion efficiency. Based on such a relation, it is demonstrated theoretically that the ultimate detectivities in multi-stage interband cascade infrared photodetectors (ICIPs) with identical discrete absorbers are the same as that...