A Charge Storage Target for Electron Image Sensing

The subject of this paper is the use and properties of a self-supporting silicon wafer containing an array of about one-half million diodes in an area of 12.5 millimeters on a side. See Fig. 1. The thickness of the substrate under the diode array is in the range 10-25 microns depending on the application. The wafer perimeter which is considerably thicker, provides increased physical strength. As an image sensing target in a vidicon type of camera tube, 1 developed for the Picturephone® station set,2 it converts incoming photons that are absorbed in the n-type conductivity substrate into hole-electron pairs. 1855 1856 T H E BELL S Y S T E M T E C H N I C A L J O U R N A L , N O V E M B E R 1968 RESISTIVE SILICON Fig. 1 -- Cross section of active target area illustrating the substrate, diodes, oxide mask, resistive sea, and scanning electron beam.