To replace the sapphire substrates commonly used in the LED industry, researchers at Osram Opto Semiconductors have manufactured 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, and Osram said they could be commercially available in about two years. 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 company is a subsidiary of Osram AG of Munich.