LED with porous diffusing reflector

US7601989B2 · kind B2 · utility

Assignee

• Philips Lumileds Lighting Company LLC · US

Inventors

• John E. Epler · San Jose, US
• Hanmin Zhao · Milpitas, US
• Michael R. Krames · Los Altos, US

Key dates

• Filing date: Mar 27, 2007
• Grant date: Oct 13, 2009
• Expiry date: Oct 19, 2027

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10H20/882

Abstract

In one embodiment, an AlInGaP LED includes a bottom n-type layer, an active layer, a top p-type layer, and a thick n-type GaP layer over the top p-type layer. The thick n-type GaP layer is then subjected to an electrochemical etch process that causes the n-type GaP layer to become porous and light-diffusing. Electrical contact is made to the p-GaP layer under the porous n-GaP layer by providing metal-filled vias through the porous layer, or electrical contact is made through non-porous regions of the GaP layer between porous regions. The LED chip may be mounted on a submount with the porous n-GaP layer facing the submount surface. The pores and metal layer reflect and diffuse the light, which greatly increases the light output of the LED. Other embodiments of the LED structure are described.