Reduction of photoconductive gain in quantum well infrared photodetectors

In this work, we show that there is a reduction of photoconductive gain g in quantum well infrared photodetectors from its classical value. The reduction is caused by the quantum nature of electron transport in these structures. On the other hand, the generation-recombination noise is unaffected by the transport model, and remains to be the same as a classical photoconductor. The reduction of g leads to an apparent noise increase in these structures, i.e., the noise gain deduced from the noise measurement is larger than g deduced from the photoconductivity measurements. We compared the present theory with existing experimental data, and found reasonable agreement.