As the light-emitting diode (LED) industry focuses on dramatically lowering costs, several manufacturers are trying to do away with the incumbent sapphire as the choice for substrate and replace it with much less expensive silicon. Recently Lattice Power announced the start of volume production of its gallium nitride (GaN)-on-silicon LEDs. Others pursuing this route include Osram Opto Semiconductors, Plessey Semiconductors and Bridgelux (Client registration required.).
Despite some early results, silicon has yet to present itself as a winner over sapphire. GaN-on-silicon LEDs are still years away from overcoming the challenge of true volume manufacturing; many of the leading companies are still about two to three years away from commercial manufacturing. What’s more, LEDs on sapphire substrates are continuing to improve in performance, creating a moving target for silicon-based LEDs. The price of sapphire has plummeted from over $450 per six-inch substrate a year ago to under $300 today. And prices are likely to decline further, especially given the increasing number of low-cost Asian manufacturers creating sapphire substrates with off-the-shelf equipment from GT Advanced Technologies and Arc Energy (Client registration required.) and other copy-cat equipment solutions. While silicon’s threat to sapphire substrates is becoming more real, it’s not the end of the road for sapphire just yet.