METHOD FOR LOWERING DARK CONDUCTIVITY OF THIN SEMICONDUCTING FILMS

摘要

1,229,006. Electrolytically treating vapourdeposited films. EASTMAN KODAK CO. Nov.28, 1968 [Nov.29, 1967], No.56520/68. Headings C7B and C7F. [Also in Division H1] The dark conductivity of a vapour-deposited ionic semi-conducting film of the oxide, sulphide, selenide or telluride of Cd, Zn or Pb, e.g. an evaporated coating of CdS on glass, is decreased by immersing the film as an anode in an electrolyte prepared by dissolving an alkali or alkaline earth metal hydroxide, sulphide, selenide or telluride, e.g. Na 2 S for CdS or ZnS, Na 2 Se for CdSe, Na 2 Te for CdTe or NaOH for lead oxide, in a suitable solvent, e.g. ethanol, a glycol, acetonitrile or tetrahydrofuran, and passing direct current between the anode and a cathode e.g. of Pt. The concentration of anion in the electrolyte may be 0À001 to 0À2N. The anode current density may be 0À025 to 250 mA/cmSP2/SP. Prior art discloses annealing the film and substrate at 350-900‹ C. in air, HCl, H 2 S and/or S vapour to modify the dark conductivity.