Innovation: Silicon-Based LED Chips
LED Chips, on the Cheap
LED bulbs have long been lauded as an energy-efficient alternative to incandescent bulbs. But LED, or light-emitting diode, bulbs are expensive to produce, which has kept retail prices high and hampered widespread adoption by consumers. Bridgelux, a manufacturer of LED components in Livermore, California, says it has a cheaper solution. Each LED bulb contains a chip made of gallium nitride, or GaN, a crystalline semiconductor that is usually grown on costly materials, including sapphire. Bridgelux has developed a way to grow GaN on low-cost silicon wafers, which could slash production costs as much as 75 percent. The chips have a light output of 135 lumens per watt, which is comparable to that of standard LED chips. Bridgelux plans to begin selling the chips to LED manufacturers by 2014.
The silicon wafers shown here measure 8 inches in diameter and are coated with a film of gallium nitride. They can be cut into small chips for LED bulbs.
Straight and Narrow
Bridgelux uses chemical vapors to prevent gallium nitride from cracking during the fabrication process.
Made to Order
Silicon wafers for LED chips can be manufactured on the same equipment used to make silicon computer chips.