GB685288A - Improvements in photocells - Google Patents

Abstract

685,288. Discharge apparatus. HILGER & WATTS, Ltd. March 16, 1949 [March 25, 1948; May 31, 1948], Nos. 8867/48 and 14115/48. Class 39(i) [Also in Group XL(b)] In the production of a photoelectric cell of the photo conductive type in which the light-sensitive layer consists of a compound containing at least one metal, the photo cell is formed by vaporising the compound or a metallic constituent thereof at a pressure considerably below atmospheric for deposition on a carrier and subjecting the material while in the vapour phase to an electric discharge in the presence of a gas, e.g. oxygen or air, capable of being adsorbed on to the particles of the vaporised material. The process may be carried out in apparatus in which the particles of the substance are produced in the space containing the ions of the gas to be adsorbed. Apparatus for producing separately the gas ions and those of the substance to be deposited is shown in Fig. 6 in which a vessel 23 in the shape of a T has a stem portion including a coil 24 producing electrons and grid electrodes 25, 26 maintained at progressively increased voltages, the gas being admitted at the inlet 3 adjacent the space between the grids. The right-hand branch of the T carries a coil 27, an accelerating grid 28 for the electrons and a heating coil 29 for the substance 13 to be deposited. Accelerating grids 30, 31 for the positive ions of the vaporised substance are held at progressively increased negative voltages, and an atmosphere of inert gas, e.g. nitrogen, is maintained by inlet and outlet tubes 32. 35 to isolate the material 13 from direct attack by the treatment gas, and the carrier 6 is mounted on a support 36 through which cooling liquid may be circulated. In other forms of apparatus a sputtering process is imployed, Fig. 1 (not shown), in which a cathode carries or is composed of the metal or compound and coils are employed to deflect the bombarding electrons from the carrier on which the substance is to be deposited. In another form, Fig. 2 (not shown) the substance is carried by a heater coil disposed between the anode and cathode, and in a further arrangement, Figs. 3, 4 (not shown), the substance carried by a coil to which suitable voltages are applied is subjected to bombardment by negative gas ions and electrons and carriers for the deposited layer are mounted above a cooling chamber. In a further arrangement, Fig. 5 (not shown), which may combine sputtering and a low voltage arc, the cathode is formed of one of the metals to be deposited with other substances in cups forming the arc. The cathode may consist of a non- sputtering metal e.g. aluminium, with different substances in the two cups.