Transient behavior of infrared photoconductors: application of a numericalmodel

A numerical model for the transient response of extrinsic photoconductors i s applied to the behavior of Ge:Ga and GaAs:Te detectors. Photoconductors d isplay a two-component response to changes in illumination. The characteris tic time and magnitude for the slow component have been studied as a functi on of background flux, applied field, temperature, device length, and signa l size. For large-signal applications, the background flux affects the tran sient response even when the signal is orders of magnitude greater than the background. Experimental results are presented to support key predictions of the modeling. Because the ratio of fast to slow components is independen t of both background and signal size, we propose the operation of detectors in such a way that final signal levels are derived from the fast component . (C) 1999 Optical Society of America.