Lumileds Lighting U.s., LLC

Philips Lumileds Lighting Company LLC

Fred A Kish

Michael Ragan Krames

Stephen Andrew Stockman

Paul Scott Martin

Michael David Camras

Daniel Alexander Steigerwald

Frank Michael Steranka

Michael Joseph Ludowise

Nicolas J Moll

Gloria E Hofler

Christopher P Kocot

Pradeep Rajkomar

Reena Khare

Nathan Frederick Gardner

Herman C Chui

Tun-Sein Tan

Tun S Tan

The extraction efficiency of a light emitting device can be improved by making the absorbing device layers as thin as possible. The internal quantum efficiency decreases as the device layers become thinner. An optimal active layer thickness balances both effects. An AlGaInP LED includes a substrate and device layers including an AlGaInP lower confining layer of a first conductivity type, an AlGaInP active region of a second conductivity type, and an AlGaInP upper confining layer of a second conductivity type. The absorbance of the active region is at least one fifth of the total absorbance in the light-emitting device. The device optionally includes at least one set-back layers of AlGaInP interposing one of confining layer and active region. The p-type upper confining layer may be doped with oxygen improve the reliability.

lll-phosphide light emitting devices with thin active layers

A light-emitting semiconductor device includes a stack of layers including an active region. The active region includes a semiconductor selected from the group consisting of III-Phosphides, III-Arsenides, and alloys thereof. A superstrate substantially transparent to light emitted by the active region is disposed on a first side of the stack. First and second electrical contacts electrically coupled to apply a voltage across the active region are disposed on a second side of the stack opposite to the first side. In some embodiments, a larger fraction of light emitted by the active region exits the stack through the first side than through the second side. Consequently, the light-emitting semiconductor device may be advantageously mounted as a flip chip to a submount, for example.

III-Phosphide and III-Arsenide flip chip light-emitting devices

III-Phospide and III-Arsenide flip chip light-emitting devices

For AlGaAs LEDs the confining layers adjoining the active layer possess the highest Al composition. From failure analysis of non-passivated, WHTOL-aged, AlGaAs LEDs, it was discovered that corrosion occurs the fastest at the exposed surfaces of the high Al-content confining layers. By placing a high-quality native oxide at the exposed surfaces of the high Al-content confining layers which protect from the formation of the 'poor' oxide, it is possible for LEDs to retain essentially their same light output after 2,000 hours of WHTOL testing. Further, it is possible to improve carrier confinement, carrier injection, wave guiding, and other properties by increasing the Al-content of different layers.

Advanced semiconductor devices fabricated with passivated high aluminum content III-V materials

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San Jose, CA, United States of America

Fred A Kish