Diamonds Wafer: Alleviating Overheating in High-power RF Devices

With more than five times the thermal conductivity of copper, diamond is the ultimate heat spreader.Researchers at the University of Illinois at Urbana-Champaign applied extreme pressure in a diamond anvil cell to metal films on diamond, and have, as a result, now determined the physical process dominating this unexplained heat flow, which has implications for understanding and improving heat flow between any two materials.

"Overheating has become a major limiting factor in the performance of high-power RF devices," said David Cahill, a professor and head of the Department of Materials Science and Engineering at Illinois. "Modern RF electronics for wireless devices such as satellites and cellphones generate so much heat in a microscopic area that the packing density and performance of RF devices isn’t limited by Moore’s Law anymore, so much as by how fast we can pull heat away from those devices. For overheating at microscopic length scales, it’s not enough to just swap out silicon for diamond; we need a microscopic understanding of how heat enters materials like diamond."

Cahill explained that this work lies more on the fundamental side of thermal physics research, although materials like diamond and silicon carbide are being actively developed as alternative substrates for high powered radio-frequency (RF) devices. "Studies of extremes like metals on diamond at high pressure are valuable because they allow us to test our ideas about what is happening in this complex problem. The experiments we designed let us test and falsify a series of hypotheses, ultimately leading to a better understanding of heat flow between dissimilar materials."

To date, the technical indicators of the existing diamond heat sinks and diamond wafer produced by CSMH have reached the world's leading level. The surface roughness of the diamond wafer growth surface is Ra<1nm, and the thermal conductivity of the diamond heat sinks could be customized from 1000-2000W/m.k. High-power semiconductor lasers using diamond heat sinks have been used in optical communications, and are also used in laser diodes, LED light-emitting diodes, power transistors, electronic packaging materials and other fields. Based on wafer-level diamond product capabilities, the company has developed GaN-on-diamond epitaxial wafers, which are mainly used in radio frequency (satellite, 5G base station) and high-power devices (photovoltaic, wind power, new energy vehicles, energy storage) and other Areas with high thermal management needs, as a complement to GaN-on-SiC materials.