Monolithic variable size detector

Abstract

There is disclosed an all silicon monolithic focal plane array of variable size infrared detectors for image detection. The structure comprises two epitaxial layers grown on an extrinsically doped silicon substrate. The detectors are formed in and extend through the substrate, the material of which is sensitive to specific wavelength infrared signals according to the dopant used in the substrate. The collection of charges takes place on a first buried layer formed around a portion of the first epitaxial layer-substrate interface, and the charges are then transferred through a third buried layer of the same conductivity type to a conducting surface layer on the upper portion of the second epitaxial layer. A second buried layer in a second portion of the epitaxial layer-substrate interface connected through a fourth buried layer to a surface layer provides a means for controlling the size of the detector region. The signal readout function is performed by a charge coupled device shift register constructed in the second epitaxial layer and includes selectively spaced electrodes in an insulating layer. Carriers generated in the detector by incident infrared radiation are collected into the first buried layer and then pass through the third buried layer to the surface layer and they are injected therefrom into the CCD shift register and are detected at the output.