Photoconductive gain and generation‐recombination noise in multiple‐quantum‐well infrared detectors

The photoconductive gain, g, and generation‐recombination (GR) noise of multiple‐quantum‐well infrared detectors are calculated for structures in which the well capture probability, pc, and the fraction of current derived from tunneling are allowed to vary through the structure. For uniform pc and no tunneling current, g=1/(Npc), where N is the number of wells. The GR noise power under the same conditions is 4eĪgB(1−pc/2), where e is electronic charge, I is the mean current, and B is the measurement bandwidth. When pc≪1, the noise contributions from carrier generation and decay (recombination) are equal as in a homogeneous photoconductor. However, when pc→1, the recombination noise decreases to zero, and the noise is equal to the shot noise of N series‐connected, independent junctions.