Browse Prior Art Database

Monolithic LED Display Arrays

IP.com Disclosure Number: IPCOM000079376D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Bartholomew, RF: AUTHOR [+3]

Abstract

Monolithic light-emitting diode (LED) displays have improved performance, by fabricating arrays of LED's in which N regions are isolated rather than P regions. The isolated N regions permit absorption coefficients to be lower, which increases the emitted light from the array. Such displays are suitable for desk-top type equipment, e.g., calculators, keypunches, terminals, and typewriters. The isolated form simplifies driving schemes and facilitates packaging.

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Monolithic LED Display Arrays

Monolithic light-emitting diode (LED) displays have improved performance, by fabricating arrays of LED's in which N regions are isolated rather than P regions. The isolated N regions permit absorption coefficients to be lower, which increases the emitted light from the array. Such displays are suitable for desk- top type equipment, e.g., calculators, keypunches, terminals, and typewriters. The isolated form simplifies driving schemes and facilitates packaging.

Monolithic displays may be fabricated, by vapor or liquid epitaxy growing a layer of N type gallium arsenide (or gallium arsenide phosphide, gallium aluminum arsenide) 10 on a P type gallium arsenide (or gallium arsenide phosphide, gallium aluminum arsenide) substrate 12. The layer 10 should have a donor concentration in the range of 1 x 10/17//cm/3/ to 3 x 10/18//cm/3/ and a thickness of 10 to 30 microns. The substrate should have an acceptor concentration in the range of 5 x 10/18//cm/3/ to 1 x 10/20//cm/3/ and a thickness of about 400 microns. A composite dielectric layer 14 is formed on the surface of layer 10.

In one form, the layer 14 may comprise comhinations of silicon nitride and silicon dioxide. Openings are formed in the layer 14 for P type isolation diffusion
16. The isolation diffusion may be into the bare surface of the layer 10 or through the bottom portion of the layer 14. In one form zinc-gallium arsenide may be employed as the P source material, to form isolated N regions 18 in the layer 10. Out-diffusion of the zinc from the substrate 12 during the diffusion cycle, will move the PN junction up from the epi substrate boundary. This effect may be enhanced by an optional heat treatment prior to diffusion. An N contact 20 may be...