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Planar Light Emitting Diodes and Arrays

IP.com Disclosure Number: IPCOM000077635D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Blum, JM: AUTHOR [+2]

Abstract

In the fabrication of high-efficiency planar light-emitting diodes (LED) it is very difficult to simultaneously achieve a diffused layer which has very little free carrier absorption, high-surface concentration, and low-sheet resistance. The present apparatus enables one to achieve the surface concentration and low-sheet resistance. This makes possible low-contact resistance while at the same time keeping the free carrier absorption low. Therefore, the light emitted at the junction comes out of the surface.

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Planar Light Emitting Diodes and Arrays

In the fabrication of high-efficiency planar light-emitting diodes (LED) it is very difficult to simultaneously achieve a diffused layer which has very little free carrier absorption, high-surface concentration, and low-sheet resistance. The present apparatus enables one to achieve the surface concentration and low- sheet resistance. This makes possible low-contact resistance while at the same time keeping the free carrier absorption low. Therefore, the light emitted at the junction comes out of the surface.

Each light-emitting diode area is formed of a number of very small, shallow diffusions so that a large number of PN junctions intersect the surface within each LED area. Since the strongest light emission from an LED occurs where the PN junction intersects the surface, this provides a light-emitting diode with high-light emission.

Referring to Fig. 1, an N-type substrate 10 has a plurality of P-type diffusions 12 therein. These diffusions extend across substrate 10 in straight lines in this embodiment. Located over the PN junctions of each diffusion are oxide layers
14. A metal contact 16 provides electrical contact to the P-type regions.

The maximum amount of light emitted by the LED of Fig. 1 comes from the P- type side of each PN junction. This light output is indicated by arrows 18. In contrast with previous light-emitting diodes, the diode of Fig. 1 has a plurality of PN junctions which intersect the surface of sub...