ELECTRON-BEAM-INDUCED OXIDATION OF CDS

Oxidation of a CdS crystal surface after 4 kV electron beam irradiation in the presence of water vapour is examined using Auger electron spectroscopy and electron energy loss spectroscopy. It is shown that not only the kinetics of the oxidation process, but also its character depend on the water vapour pressure in the range 10(-7) to 4 x 10(-9) Torr. It was found that in the case of 10(-7) Torr sulphur oxyanions are formed on the CdS surface after irradiation, whereas in the case of 4 x 10(-9) Torr these oxyanions are not detected even after prolonged irradiation. In the latter case a depletion of surface sulphur atoms takes place and a bulk-like CdO overlayer is formed.