A method is described for facilitating the estimation of the background current that is generated by an infrared photodetector, based on the development of an idealized rectangular photon-responsivity spectrum that incorporates the detailed influence of the actual responsivity spectrum within the values of its predetermined parameters. Background currents may then be calculated algebraically without undue loss of precision by use of standard blackbody radiation formulas. Values of the parameters defining the idealized spectrum are derived for the majority of photodetectors in common use today, including silicide Schottky-barrier devices, and are applied within several examples of background-current estimation.
Owen M. Williams, "Infrared-photodetector background-current estimation," Appl. Opt. 31, 497-503 (1992)