By switching from sapphire to silicon wafers, the wafer size jumps from two or four inches to eight inches.

FORBES: How Silicon Will Spur A Boom In Solid-State Lighting

At present these LEDs are made in machines similar to those used to make silicon chips, by depositing layers of gallium nitride on sapphire-based wafers.

ECONOMIST: Lighting: A brilliant new approach | The

Gallium nitride, or GaN, converts electrical impulses to light and is grown on the surface of wafers made from sapphire or silicon carbide.

FORBES: How Silicon Will Spur A Boom In Solid-State Lighting