To replace the sapphire substrates commonly used in the LED industry, researchers at Osram Opto Semiconductors have manufactured the first high-performance blue and white LED prototypes in which gallium-nitride layers are grown on 6-in. silicon wafers. The new chips, which are already in the pilot stage, are being tested under practical conditions. Osram said they could be commercially available in about two years. This diagram shows the production of a UX:3 chip on a silicon wafer. (Images: Osram) Silicon is an attractive, low-cost option for large-volume fabrication. Quality and performance data on the fabricated LED silicon chips match those of sapphire-based chips: the blue UX:3 chips in Osram’s Golden Dragon Plus package achieve a brightness of 634 mW at 3.14 V, equivalent to 58 percent efficiency. When combined with white LEDs, the prototypes correspond to 140 lm at 350 mA, with an efficiency of 127 lm/W at 4500 K. Component costs must come down significantly to bring these new LEDs to the lighting industry, said Dr. Peter Stauss, project manager at Osram. New methods are already in development along the entire manufacturing chain to lower costs, while maintaining the same level of performance. Osram high-performance LED chips based on InGaN technology today are fabricated on wafers 6 in. in diameter. Larger silicon wafers could increase productivity even more; researchers have demonstrated the first structures on 200-mm substrates. Osram’s research was funded through the German Federal Ministry of Education and Research’s “GaNonSi” project network. A subsidiary of Osram AG, Osram Opto Semiconductors delivers solutions based on semiconductor technology for lighting, sensor and visualization applications. For more information, visit: www.osram-os.com