Photocapacitive detector array

Abstract

A photocapacitive image detector array comprises a matrix of M.times.N spaced columns of relatively high carrier concentration extending between first and second opposite faces of a semiconductor substrate having a relatively low carrier concentration. N parallel spaced electrode stripes extend in the X direction on the first face and M parallel spaced semiconductor stripes of intermediate carrier concentration extend in the Y direction on the second face. Stripe k of the N stripes makes ohmic contacts with each of the M columns, where k=1,2, . . . N. Stripe p of the M semiconductor stripes makes contact with each of the N columns, where p=1, 2, . . . M. Each of the M regions has a depletion layer having a thickness adapted to be modulated by radiation from an image to be detected. M parallel spaced electrode stripes extend in the Y direction so that stripe q of electrode stripes M is in registration with semiconductor stripe q, where q=1, 2, . . . M. A composite insulating layer, including two insulating thin films, is sandwiched between the M electrode stripes and M semiconductor stripes. Thereby M.times.N pixels are formed, with each pixel being associated with a different one of the columns. The composite insulating layer and M electrodes are transparent to radiation from the image so that the image incident on the semiconductor stripes modulates the thickness of the depletion layers of the semiconductor stripes to vary the capacitance at each pixel as a function of the radiation intensity incident thereon.