Photoluminescent Properties of Vacuum Deposited Cadmium Sulfide Films

摘要

Green and blue photoluminescence has been observed below 100 degrees K in vacuum deposited, low resistivity CdS films given no post deposition treatment. The films were deposited in a heated chamber inside the bell jar on fused quartz substrates held at temperatures from 140-180 degrees C. The background pressure in the vacuum system was 0.000 001 Torr. The evaporant used was chlorine-doped CdS powder. The chlorine doping activated the luminescence and gave films that had resistivities at 300 degrees K in the range of from 1 to 100 ohm-cm parallel to the substrate. The green luminescence in the films at 77 degrees K was similar to the emission reported for donor-doped CdS. The green emission spectra observed at 10 degrees K became better resolved than at 77 degrees K, and the peak position shift with temperature was small. The blue emission peak observed in the films was at 4892 A at 77 degrees K, which is in the fundamental absorption edge. Some of the literature relating to the theory and practice of CdS vacuum deposition is reviewed. Also a summary of the properties of the green luminescence of pure and donor-doped CdS is given. (Author)