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Optical Detector for Short Wavelength Light

IP.com Disclosure Number: IPCOM000076284D
Original Publication Date: 1972-Feb-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Jacobus, W: AUTHOR [+2]

Abstract

This is a photodetector for short-wavelength light and fabricatable with basic field-effect transistor (FET) technology.

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Optical Detector for Short Wavelength Light

This is a photodetector for short-wavelength light and fabricatable with basic field-effect transistor (FET) technology.

Optical detectors for memory array applications have laser radiation of 5,0000 angstroms or less as the energy for detection. Conventional diffused photodetectors with junction depths less than one micron would be needed for these applications and their fabrication is not practical.

In accordance with the drawing, individual photodetectors for an array consist of a single N+ diffusion into a P-substrate 10. Contact to the substrate is by aluminum metallization 12 which is insulated from the substrate by a dielectric layer 14, consisting of silicon dioxide. Contact to the N+ region is by aluminum conductor 12', which is similarly insulated from the substrate by silicon dioxide layer 14'. Gate 20 consists of a conductive transparent material, such as SbO, which is separated from the substrate by a dielectric layer 18 of a silicon dioxide material. The layer 18 is relatively thin in the order of 500 to 1000 angstroms.

The photodetector operates by applying a positive potential to the gate creating an N channel inversion layer which becomes an extension of the PN junction, as shown by dotted lines in the drawing. Light impinging on the gate region through the transparent gate electrode generates hole-electron pairs under the electrode. In order to select a particular diode in an array, a positive voltage...