OSRAM Opto Semiconductors Introduces New, Blue, Thin-Film LEDs Based on Indium Gallium Nitride - ThinGaN Technology

SAN JOSE, Calif.--Sept. 3, 2003--OSRAM Opto Semiconductors announces an industry first: the introduction of blue thin-film LEDs that will successfully enable applications of far-reaching significance, including the future use of LEDs in vehicle headlights.

Developed as a result of the new, indium gallium nitride-based, ThinGaN technology, blue, thin-film LEDs by OSRAM Opto Semiconductors make it possible to extract up to 75% of the internally generated light from the chip.

The new LEDs technology represents the most efficient way to extract it from the semiconductor crystal. The standard substrate material for blue LEDs is based on InGaN is SiC (silicon carbide), with a typical substrate thickness of 250 um. Chemically and mechanically it is very stable and cannot be completely removed with either a wet chemical process or dry chemical plasma processes without also destroying the 5 um thin InGaN epitaxial layer.

Alternatively, sapphire (Al2O3) is suitable as a standard substrate for InGaN epitaxy. However, the material properties of sapphire cause major distortions and defects during InGaN growth, which reduce the internal luminous efficacy.

OSRAM Opto Semiconductors has tailored the epitaxial procedure specifically to this material and at the same time developed a method for careful removal of the substrate material. In the world's first production-scale laser lift-off plant, the light from a pulsed UV laser splits up the semiconductor material into its components. It is then cleanly separated from the sapphire substrate.

Other key factors for the exceptionally high efficiency of these ThinGaN LEDs are the optimized surface roughness, low optical losses in the LED itself and mirror metalization as a reflector tailored to this material combination. Prototypes of 5 mm-radial LEDs achieve brightness values of up to 16 mW for the blue products (460 nm) at an operating current of 20 mA.

Series production for OSRAM Opto Semiconductors blue thin-film LEDs expected to start in 2004.

About OSRAM Opto Semiconductors

OSRAM Opto Semiconductors GmbH of Regensburg is a wholly owned subsidiary of OSRAM, one of the three largest lamp manufacturers in the world. It offers its customers solutions based on semiconductor technology for lighting sensor and visualization applications. The company has sites in Regensburg (Germany), San Jose (USA) and Penang (Malaysia). In the 2002 fiscal year (ending in September), around 3370 employees produced sales of EUR 309 million.

Further information: www.osram-os.com