Sapphire is key to producing white LEDs. It's artificially grown, rather than being dug up from the rock, but it's pretty much the same as the precious gem material you're probably thinking of--meaning it's rather expensive. Slabs of crystalline sapphire about 4-inches in size act as a substrate during LED production: The complex layered recipe of semiconductor chemicals that actually make up the LED devices is "grown" in various process on the precise surface of the sapphire, and then cleaved from it at the end before being chopped up and packed into the more familiar dome-shaped LED unit.
But sapphire is part of the main problem facing wider adoption of LED lighting--it makes the cost of high-brightness white LED light bulbs prohibitive compared to compact fluorescent bulbs, and many times more expensive than incandescent bulbs.
Research started by Bridgelux has resulted in a radical shift--Gallium-nitride LEDs can now be grown on silicon substrates for the first time in a "commercial grade." The tech leverages the huge, ultra precise and far cheaper silicon wafers that are used in silicon chip manufacture instead of the smaller, more expensive sapphire ones. The breakthrough has been to successfully grow white LEDs on a silicon substrate to create devices that produce 135 lumens per watt of electrical power--well above what typical CFL bulbs can offer, and around 10 times better than old incandescent bulbs.
This breakthrough in producing light emitting diodes could see LED production costs tumble as much as 75%. Ten times greater electrical efficiency, ten times the lifespan of old bulbs and a much more affordable cost? Yup--soon every light you encounter may be an LED one.
Print