In a photoconductive @R05054@ an @E01935@ is applied across the absorbing region and causes a current to flow in proportion to the irradiance if the photon energy exceeds the energy gap between the @V06588@ and the @C01244@. Depending on their @R05347@, photoconductive detectors are divided into photoconductive detectors for the @VT07496@ @W06659@ range e.g. cadmium sulfide or CdS photoconductive detectors, photoconductive detectors for the near @IT07399@ @W06659@ range e.g. lead sulfide or PbS photoconductive detectors, photoconductive detectors for the @IT07399@ @W06659@ range e.g. silicon doped with arsenide or Si:As photoconductive detectors, and the mercury-cadmium-telluride or HgCdTe photoconductive detector.