Abstract: An improved MOS photodetector having polysilicon gate material which is made more transparent to visible light by the addition of up to 50% carbon, and preferably about 10% carbon. The surfaces of the polysilicon-carbon gates are oxidized to form a silicon dioxide dielectric layer, thus eliminating the need to deposit a separate dielectric layer for isolation of adjacent gates in an overlapping gate array. The elimination of a separate dielectric layer permits all gates to be formed directly on the substrate dielectric layer, thus providing a uniform drive voltage requirement across the array.

Abstract: A process for forming an insulating layer of silicon dioxide in a silicon substrate that surrounds and electrically insulates a semiconductor device is disclosed herein. The process comprises the steps of forming a recess on the outer surface of the silicon substrate that encompasses the site of the semiconductor device by photo-resist patterned reactive ion etching, and then removing silicon on the surface of the resulting recess whose crystal structure has been damaged by the reactive ion etching. Next, dopant atoms are selectively deposited on the surface of the recess so that the surface of the recess might be rendered into a porous layer of silicon when immersed in hydrogen fluoride and subjected to an electrical current. Prior to the porousification step, silicon is epitaxially grown within the walls of the recess to form the site for a semiconductor device.