GaN substrate firm targets June launch
A British company looks set to open up the currently limited supply of free-standing GaN substrates, as it moves into pilot production.
Wang Nang Wang, founder of University of Bath spin-out NanoGaN, says that progress on wafer yields and quality should see a commercial launch around June 2009.
“We are now producing free-standing GaN in collaboration with our Japanese partners to get the full characterized specification,” Wang said.
With two vertical hydride vapor-phase epitaxy (HVPE) systems already in place NanoGaN is also in the process of planning its next expansion stage.
“It is now time to seek further funding or production partners to expand the production capacity,” Wang says.
“NanoGaN is focusing on getting free-standing 2-inch GaN onto the market with good quality and quantity, satisfying our customers.”
After being founded in February 2008 with a £250,000 ($350,000) seed from University of Bath s “Sulis” commercialization fund, NanoGaN gained another £500,000 in June 2008 from private investors.
That second investment round was partly spent on building a vertical HVPE system according to NanoGaN s patented design, in collaboration with a commercial MOCVD equipment manufacturer.
The bulk material that is later sliced into NanoGaN s substrates is deposited onto a buffer of GaN nanocolumns formed on top of a SiC, silicon, or sapphire substrate.
In other bulk GaN manufacturing methods this initial use of non-native substrates is a source of poor wafer quality. The lattice mismatch and differing coefficients of thermal expansion between the substrate material and GaN cause bowing and cracking as the boule cools down.
The strain that builds up in these circumstances is relieved by the nanocolumns in NanoGaN s approach, allowing thicker and better-quality bulk crystals.
The nanocolumn template wafers have recently been used to make bulk GaN in different reactors in the US and have been shown to work well, says Wang. Now the real-world effectiveness of the substrates is being assessed by NanoGaN's partners.
“We have to prove that our products have much lower bowing and strain,” Wang explained.
“We also need feedback from manufacturers to validate that free-standing GaN products provide the benefit of improved yield rate in laser diode and high power thin GaN LED fabrication.”
