TELEVISION CAMERA TUBES

摘要

1308707 Image pick-up tubes SIEMENS AG 2 Dec 1970 [3 Dec 1969] 57158/70 Heading HID A target for a camera tube comprises a transparent signal plate 1, Fig. 3, of N-type semiconductor material which carries on one side a plurality of separate P-type layers 8 forming individual flat junctions separated by respective trenches 9, each P-type layer being covered by a discrete metal layer 7 at least equal in area to the underlying junction. Preferably the surfaces of the trenches are oxidized to provide insulating layers 10. In the example illustrated the areas 7 and 8 are square in plan but they may be rectangular, hexagonal, or polygonal. The trenches may have a surface width between 1/ 5 and 1/ 10 of the width of the neighbouring P-type layers, and the width of each metal layer 7 may be equal to that of the electron beam used to scan the target. Electrode processing.-An N-type silicon plate is treated to form an overall layer of P-type material defining a single flat junction, and a precious metal such as gold or platinum is vaporized through a mask on to the surface to form the islands 7. The trenches 9 are formed by etching with a mixture of hydrofluoric acid and nitric acid, followed by oxidation of the surfaces 10 preferably by anodic oxidation in a gas discharge. In an alternative process the prepared P-type surface of the silicon plate is covered with silver which is thermally cracked to form a mosaic of irregularly shaped mutually insulated metal islands. The semi-conductor material may be a compound, either a III-V compound or a II-VI compound.