Photosensitive electrodes and methods of making same

摘要

1,008,986. Semi-conductor devices; television pick-up tubes. HITACHI Ltd. May 14, 1963 [May 25, 1962], No. 19093/63. Drawings to Specification. Headings H1D and H1K. A photo-sensitive electrode for Vidicon and other pick-up tubes comprises a substrate bearing a single-layer film of photo-conductive material, the film having been formed by vapour deposition in an atmosphere which was varied in pressure in a continuous fashion so that the film has a porosity varying through its thickness. In the embodiment described, antimony trisulphide is deposited in an argon atmosphere on to a glass substrate bearing a transparent conductive film. The time necessary for the requisite deposit is predetermined, and in the embodiment is five minutes. The apparatus is arranged such that in this time, during deposition, the argon pressure is increased in proportion to the time elapsed from an original of 10-5 mm. Hg to a pressure of 10-1 mm. Hg. The film formed varies linearly from an initial extremely compact solid to a porous structure formed at the higher gas pressure. In the single Figure (not shown), the performance of the electrode is compared with two and three layer prior act constructions. The change of gas pressure need not be proportional to time, thus the porosity gradient in the film may be readily controlled.