Light emitting devices with improved light extraction efficiency

US8628985B2 · kind B2 · utility

Assignee

• Philips Lumileds Lighting Company LLC · US

Inventors

• Michael D. Camras · San Jose, US
• Michael R. Krames · Los Altos, US
• Wayne L. Snyder · Palo Alto, US
• Frank M. Steranka · San Jose, US
• Robert C. Taber · Palo Alto, US
• John Uebbing · Palo Alto, US
• Douglas W. Pocius · Fremont, US
• Troy Trottier · San Jose, US
• Christopher H. Lowery · Chester, US
• Gerd O. Mueller · San Jose, US
• Regina B. Mueller-Mach · San Jose, US

Key dates

• Filing date: Oct 4, 2011
• Grant date: Jan 14, 2014
• Expiry date: Oct 4, 2031

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10H20/819

Abstract

Light emitting devices with improved light extraction efficiency are provided. The light emitting devices have a stack of layers including semiconductor layers comprising an active region. The stack is bonded to a transparent lens having a refractive index for light emitted by the active region preferably greater than about 1.5, more preferably greater than about 1.8. A method of bonding a transparent lens to a light emitting device having a stack of layers including semiconductor layers comprising an active region includes elevating a temperature of the lens and the stack and applying a pressure to press the lens and the stack together. Bonding a high refractive index lens to a light emitting device improves the light extraction efficiency of the light emitting device by reducing loss due to total internal reflection. Advantageously, this improvement can be achieved without the use of an encapsulant.