Anvil Semiconductors Ltd of Coventry, UK has been awarded a grant by the UK's Technology Strategy Board (TSB) to evaluate the feasibility of using its unique stress relief technology to enable the production of low-cost, high-brightness LEDs on large-diameter silicon substrates.
Anvil was spun off in August 2010 from the University of Warwick's School of Engineering by its technology commercialization subsidiary Warwick Ventures Ltd in order to exploit patented developments in SiC power semiconductor technology. Anvil says that its approach to SiC switches should cost no more than their silicon counterparts. This involves growing a thin layer of cubic SiC (3C-SiC) on silicon substrates sufficient to fabricate active power devices. In addition to the fundamental crystal growth expertise, Anvil has IP relating to resolving the problem of the stress that inevitably arises when growing SiC on Si (which to date has prevented widespread adoption of the technology). The IP has been proven on 100mm-diameter silicon wafers and can be migrated onto larger wafer diameters without modification.
Fabricating gallium nitride (GaN)-based LEDs on large-diameter silicon wafers is recognized as a key path to reducing the cost of lighting systems and displays. However, existing techniques used to manage the large mismatches in lattice parameter and thermal coefficient of expansion between silicon and GaN are complex and costly and have struggled to deliver materials suitable for high-efficiency devices, says Anvil. However, with the growth of GaN-based LED structures on SiC already well established, high-quality 3C-SiC on silicon produced using Anvil's proprietary stress relief technology could provide an alternative that can be readily migrated onto 150mm diameter substrates and beyond, the firm reckons.
The grant will fund work to produce and characterize typical GaN-based epilayers on Anvil's 3C-SiC on silicon wafers. With Anvil's process able to produce high-quality 3C-SiC surfaces with orientation close to (100), the project will also explore the technology's potential for producing the elusive cubic and, importantly, non-polar form of GaN. If successful, this could pave the way for further device benefits including improved LED efficiencies and lower-power-consumption displays, it is foreseen.
"We're delighted to have been given this opportunity to explore the potential for Anvil's technology in another exciting market," comments CEO Jill Shaw. "If we're successful, we will be looking for partners to help us take it forward."
