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Browse Prior Art Database

Electroluminescent Display Devices

IP.com Disclosure Number: IPCOM000091523D
Original Publication Date: 1968-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Rupprecht, HS: AUTHOR [+2]

Abstract

The opaque nature of a substrate is used for optical masking purposes on a layer previously grown on it. After a PN junction layer of Ga(1-x)Al(x)As is epitaxially grown from solution on opaque GaAs, removal of portions of the GaAs provides a light emitting pattern. Using ultrasonic cutting or chemical etching techniques, the GaAs substrate is partially removed. Junction continuity in the Ga(1-x)Al(x)As is broken up, yielding the structure in drawing A. As in drawing B, a monolithic alpha numeric display unit is obtained. For enhanced light output, the grooves in drawing B can be filled with antireflecting material, e.g., epoxy.

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Electroluminescent Display Devices

The opaque nature of a substrate is used for optical masking purposes on a layer previously grown on it. After a PN junction layer of Ga(1-x)Al(x)As is epitaxially grown from solution on opaque GaAs, removal of portions of the GaAs provides a light emitting pattern. Using ultrasonic cutting or chemical etching techniques, the GaAs substrate is partially removed. Junction continuity in the Ga(1-x)Al(x)As is broken up, yielding the structure in drawing A. As in drawing B, a monolithic alpha numeric display unit is obtained. For enhanced light output, the grooves in drawing B can be filled with antireflecting material, e.g., epoxy.

The Ga(1-x)Al(x)As semiconductor ternary compound can be grown from solution by liquid phase epitaxy. The homogeneity of composition is determined primarily by control of the cooling rate when the solution or melt composition is maintained essentially constant. By maintaining the cooling rate constant, a layer is grown with essentially uniform composition. By doping and counter- doping sequentially with semiconductor dopants at an interface in the growing crystalline structure, there is provided a PN junction at that interface.

A Ga(1-x)Al(x)As layer is grown on the (100) face of GaAs with a melt composition of 20 gm Ga and 0.1-012 gm Al, plus excess GaAs during a cooling rate set between 0.5 degrees C/min. to 0.1 degrees C/min. over the temperature range 1000 degrees C to 860 degrees C. Dopants for the...