High fill-factor ac-coupled x-y addressable schottky photodiode array

Abstract

Each unit cell of a Schottky barrier photodiode imaging array comprises a Schottky metal electrode formed on a silicon substrate. The Schottky electrode is reverse biased with a pulse for beginning a sensing interval, following which the change in charge on the electrode is related to the quantity of incident infrared radiation. For X-Y addressable readout, a row electrode and a column electrode are capacitively coupled to each Schottky electrode and connected to row and column address lines. For low overlap capacitance and low stray capacitance, the row and column electrodes are concentric within each cell and coplanar above the Schottky electrode. Over the row and column electrodes is an address line insulating layer, and sets of row and column address lines are coplanar over this layer. Separate segments of each row address line extend between adjacent electrode portions of correspondingly adjacent unit cells, and each column address line extends across a plurality of unit cells between the row address line segments. The address lines are connected to the underlying readout electrodes through contact windows in the address line insulating layer.