Blue light-emitting diode with high external quantum efficiency

US5416342A · kind A · utility

Assignee

• Cree Research Inc. · US

Inventors

• John Edmond · Durham, US
• Hua-Shuang Kong · Cary, US

Key dates

• Filing date: Jun 23, 1993
• Grant date: May 16, 1995
• Expiry date: Jun 23, 2013

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10H20/835

Abstract

A light emitting diode is disclosed that emits light in the blue portion of the visible spectrum with high external quantum efficiency. The diode comprises a single crystal silicon carbide substrate having a first conductivity type, a first epitaxial layer of silicon carbide on the substrate and having the same conductivity type as the substrate, and a second epitaxial layer of silicon carbide on the first epitaxial layer and having the opposite conductivity type from the first layer. The first and second epitaxial layers forming a p-n junction, and the diode includes ohmic contacts for applying a potential difference across the p-n junction. The second epitaxial layer has side walls and a top surface that forms the top surface of the diode, and the second epitaxial layer has a thickness sufficient to increase the solid angle at which light emitted by the junction will radiate externally from the side walls, but less than the thickness at which internal absorption in said second layer would substantially reduce the light emitted from said top surface of the diode.