January 12, 2012 — OSRAM Opto Semiconductors manufactured high-performance 1mm2 blue and white light emitting diode (LED) prototypes, growing the light-emitting gallium-nitride (GaN) layers on 150mm silicon (Si) wafers rather than sapphire substrates.
OSRAM’s researchers report no loss of LED quality in the pilot run. The blue UX:3 chips in OSRAM’s standard Golden Dragon Plus package achieve 634mW brightness at 3.15V, equivalent to 58% efficiency; white LEDs, using a conventional phosphor converter in a standard housing, showed 140lm at 350mA with an efficiency of 127lm/W at 4500K. The new LED chips are being tested under practical conditions, and OSRAM LEDs-on-Si could hit the market in as little as two years.
|Figure 1. The production of a UX:3 chip on a silicon wafer. SOURCE: OSRAM.|
Silicon offers a lower-cost alternative to sapphire substrates, and silicon wafer processing in larger diameters is already widespread in the semiconductor market, potentially enabling large-volume LED fabrication. New chip technology, production processes, and housing technologies will enable a switch to silicon-based LED manufacturing, said Dr. Peter Stauss, project manager at OSRAM Opto Semiconductors. Today, LED makers can fabricate over 17,000 1mm2 LED chips on a 150mm wafer. Larger silicon wafers could increase productivity even more; researchers have demonstrated the first structures on 200mm substrates.
|Figure 2. OSRAM high-performance LED chips based on InGaN technology today are fabricated on 6" wafers. SOURCE: OSRAM.|
Lowering component costs while maintaining quality and performance [of sapphire-based LEDs] opens up the lighting application sector, said Stauss.
OSRAM Opto Semiconductors has acquired comprehensive expertise over the last 30 years in the process of artificial crystal growth (epitaxy), the foundation for this milestone in the development of new manufacturing technologies. The German Federal Ministry of Education and Research funds these activities as part of its “GaNonSi” project network.
OSRAM AG (Munich, Germany) is a wholly-owned subsidiary of Siemens AG and a leading light manufacturer. Its subsidiary, OSRAM Opto Semiconductors GmbH, offers semiconductor-technology-based products for lighting, sensor and visualization applications. For more information, go to www.osram-os.com.