Patent GB-1116676-A (GB)
Title: Photosensitive semiconductor devices and process for the manufacture thereof
IPC: G11B23/027
Filed: 1967-03-08
Abstract: 1,116,676. Photo-sensitive devices. NATIONAL CASH REGISTER CO. 8 March, 1967 [21 April, 1966], No. 10912/67. Heading H1K. The substrate for a sprayed photo-sensitive film 3 comprises a thin, flexible anodized aluminium foil, the oxide layer 2 insulating the film 3 from the aluminium 1. The film 3, composed for example of photo-conducting sulphides and/or selenides of Zn, Hg and Cd, is sprayed on, preferably using the method of U.K. Specification 970,017, and is activated by heating in contact with a sintered powder including Cu and Cl atoms, as described in Specification 1,051,085. A continuous flow process is described (Fig. 4, not shown) in which the film 3 is applied to a ribbon of anodized aluminium foil temporarily held on a platen by vacuum, electrodes 4 or 5, e.g. of In, are vacuum evaporated on through a mask, leads of tinned Cu are attached to the electrodes by ultrasonic welding with In or by bonding with silvercarrying epoxy adhesive, and each device is coated with a layer of transparent plastics material, e.g. by spraying and heat- and pressure-bonding, by rolling, or by dip-coating. Finally, individual devices are stamped out of the foil. Individual devices are encapsulated either in metal cans or in transparent insulating envelopes. A photovoltaic cell is described in which a junction exists between films (43, 44), Fig. 5 (not shown), of CdS and Cu x Sy respectively. A contact layer (42) of conductive tin oxide is applied to the anodized aluminium substrate by spraying on SnCl 4  while the substrate is heated, the layers (43, 44) being applied as disclosed in Specification 970,017. A grid electrode (45) of Sn, Cu, Ag or Au is then deposited by vapour deposition, silk screening or electrodeposition, and a transparent plastics protective layer (46) is applied over the grid. Fig. 6 (not shown) discloses a contactless potentiometer in which a photo-conductive film (52), e.g. of CdS, ZnS or CdSe applied as described above to a flexible anodized aluminium substrate, is disposed completely around the inner wall of a hollow cylinder (57), and separates a highly conductive area (53), e.g. of In from a relatively highly resistive area (51), e.g. of resistive paint or a silk-screened cermet metal composition. A lamp (55) is positioned within the cylinder, screened from the photo-conductive film (52) by a rotatable inner cylinder (54), in which is a longitudinal slit (56). Rotation of the inner cylinder (54) varies the peripheral position of the photo-conducting path induced in the film (52) by light passing through the slit (56), and hence varies the relative path lengths within the conducting film (53) and resistive film (51) respectively, between external contacts (50-50b or 50b-50c). The total resistance between the external contacts is thus variable in a contactless manner. A photo-conductive matrix is disclosed, Fig. 7, 7a (not shown), in which crossed electrode systems (63, 65) are deposited on a photoconducting film (62) coated on to an anodized aluminium foil as previously described. The electrodes are insulated from one another at their intersections by a dielectric layer (64), e.g. of plastics, glass or silica.