PHOTOCONDUCTIVE PROPERTIES OF CHEMICALLY DEPOSITED CDS - DY FILMS

The photoconductive CdS : NaF, Dy films have been prepared by chemical bath deposition technique. Photocurrent to darkcurrent ratios of the order of 10(5) are observed. From the optical micrographic studies the particle sizes for different dipping times and dopant concentrations have been determined in terms of which the growth conditions are also discussed. Transmission spectra for the CdS; CdS : NaF and CdS : NaF, Dy films have been reported showing sharp transitions corresponding to the band gap of CdS. Studies on excitation spectra of these films show a strong peak in all the cases corresponding to band gap of CdS representing intrinsic excitation, along with the peaks due to impurities. Rise and the decay of the photocurrent have been studied at different temperatures below room temperature. By peeling of the decay curves into a possible number of exponentials, trap depths have been calculated for different cases.