Luxembourg-registered synthetic diamond materials firm Element Six (a member of the De Beers Family of Companies) says that its gallium nitride (GaN)-on-diamond wafers have been proven by Raytheon Company to significantly outperform industry-standard gallium nitride-on-silicon carbide (GaN-on-SiC) in RF devices — reducing thermal resistance, increasing RF power density, and preserving RF functionality.
In high-electron-mobility transistor (HEMT) devices, Raytheon achieved a three times improvement in GaN-on-diamond’s RF areal power density compared with GaN-on-SiC devices, says Element Six. The GaN-on-diamond devices also demonstrated a nearly three times reduction in thermal resistance, it adds. Raytheon used several industry-standard thermal measurement techniques, including time-domain thermal reflectance (TDTR), laser flash and resistance thermometry, as well as finite-element modeling, to establish the consistency of the results.
Upon reaching these milestones, Raytheon has met the aggressive objectives of the US Defense Advanced Research Project Agency’s (DARPA) Near Junction Thermal Transport (NJTT) program, which aimed to develop GaN RF devices that exhibit three times or greater improvement in power density through improved thermal management.
Element Six claims that its GaN-on-diamond substrates exhibit an advantage over other substrate materials because synthetic diamond dissipates heat up to five times more effectively than silicon or silicon carbide. This, coupled with the close proximity of the diamond to the GaN, results in a dramatic reduction in the thermal resistance of GaN-on-diamond wafers. Lower thermal resistance enables simpler and less expensive thermal management systems and reliable operation in higher ambient temperatures, as well as more cost-effective RF devices.
“Heat issues account for more than 50% of all electronic failures, and limit GaN’s inherent power-density performance potential,” says Adrian Wilson, director of Element Six Technologies Group. “RF and high-voltage power device manufacturers that leverage GaN-on-diamond will have access to unmatched wafer thermal conductivity, and be able to deliver rapid, efficient and cost-effective heat extraction,” he adds. “As the first company to make GaN-on-diamond wafers commercially available, we look forward to collaborating with manufacturers to tap into the unique properties of synthetic diamond.”
Having been designed for manufacturers of transistor-based circuits with high-power, high-voltage and high-frequency characteristics, Element Six reckons that its GaN-on-diamond wafers can lead to the creation of smaller, faster, more energy-efficient and higher-power electronic devices that have longer lifespans and improved reliability. GaN-on-diamond technology offers advantages over all other available RF semiconductor materials, delivering superior system performance and cost, the firm claims, making it suitable for next-generation device technology in both defense and commercial applications.
