GaN-on-silicon material technology has been in development at CNRS – CRHEA, a world-leading research center for GaN materials, since the late 1990s. A key physical challenge is presented by the different thermal coefficients of the two materials GaN and silicon. This makes it difficult to manage the stress on a GaN film grown on silicon by MOCVD (metal organic chemical vapor deposition) material epitaxy technology and avoid cracking the film during cool down over a wide temperature range (1,000° C down to 25° C). The entire process must be performed while maintaining extreme flatness with less than 20 microns of curvature across a 200-mm substrate.
CNRS-CRHEA teams were among the first in the world to discover and patent a GaN-buffer technology that enables the growth of thick, high-quality GaN material on a silicon substrate.
Since 2003, this technology has been exclusively developed by Picogiga and later by Soitec for various applications including power RF, power switching and optoelectronics.
In 2012, Soitec and CEA-Leti joined forces to develop a 200-mm, CMOS-compatible, GaN-based FET technology, leveraging Soitec’s proprietary and optimized material technology, to address the technical and economic challenges of 650-volt and 1,200-volt power switching.
That technology has since been transferred to Exagan to accelerate the product industrialization and market penetration of GaN-based devices for high-power switching.