GaN-on-insulator wafers could be tailor-made
Picogiga International, the French substrate supplier, has made what is believed to be the world's first single-crystal GaN-on-insulator substrate.
According to the Soitec subsidiary, the technology could lead to improvements in the performance of GaN-based devices such as blue and white LEDs and high-power microwave components.
Silicon-on-insulator technology has already penetrated the mainstream electronics market, resulting in improved device performance.
Picogiga told Compoundsemiconductor.net that the substrates, which are made using the commercial "Smart Cut" process that Soitec employs to manufacture silicon-on-insulator wafers, will allow homo-epitaxial growth of active GaN structures.
This will mean that devices based on the wide-bandgap material will have better quality than those grown using current hetero-epitaxy, both in terms of dislocation density and stress, added the company.
"The carrier material (backside wafer) will be selected independently from the topside layer," said Picogiga. "That will allow the substrate to be tailored and optimized for thermal management, packaging and assembly, or mechanical stress management."
The procedure should help to reduce the thermal limitations of bulk GaN material in RF transistors, while it could also help to improve LED efficiency.
Picogiga has so far produced only 2-inch diameter GaN-on-insulator wafers, but says that the technique will be suitable for larger substrates as soon as these become available.
However, production quantities of GaN-on-insulator wafers will be unavailable until bulk GaN substrates become more affordable and widely used, with Picogiga not expecting commercialization until 2006 or 2007.
But the company did say that it had several customers who were "eager to try" the engineered substrates.
