Determination of the Energy Gap in Photoconducting Insulators Through Current Noise Measuremen

Abstract

ABSTRACTMeasurements of the current noise power spectrum of the photoconducting insulators CdS and CdSe irradiated with monochromatic light of different wavelength A are reported.It is shown that there is an abrupt change of about one order of magnitude in the low frequency power density of the noise when A crosses the photoconductor gap value Ag and the photocurrent and the device conductance are kept constant by varying the light intensity.The effect is explained in terms of an abrupt increase of the carrier recombination rate when the photon energy becomes larger than the energy gap of the photoconductor. Possible applications of these results are briefly discussed.