Laterally contacted blue LED with superlattice current spreading layer

US8395165B2 · kind B2 · utility

Assignee

• Bridgelux, Inc. · US

Inventors

• Zhen Chen · Stanford, US
• William Fenwick · Livermore, US
• Steve Lester · Palo Alto, US

Key dates

• Filing date: Jul 8, 2011
• Grant date: Mar 12, 2013
• Expiry date: Sep 8, 2031

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10H20/816

Abstract

A laterally contacted blue LED device involves a PAN structure disposed over an insulating substrate. The substrate may be a sapphire substrate that has a template layer of GaN grown on it. The PAN structure includes an n-type GaN layer, a light-emitting active layer involving indium, and a p-type GaN layer. The n-type GaN layer has a thickness of at least 500 nm. A Low Resistance Layer (LRL) is disposed between the substrate and the PAN structure such that the LRL is in contact with the bottom of the n-layer. In one example, the LRL is an AlGaN/GaN superlattice structure whose sheet resistance is lower than the sheet resistance of the n-type GnA layer. The LRL reduces current crowding by conducting current laterally under the n-type GaN layer. The LRL reduces defect density by preventing dislocation threads in the underlying GaN template from extending up into the PAN structure.