This patterned diamond surface covered with a layer of atom-thick graphene can efficiently transport phonons from a semiconductor to a diamond heat sink. Image: Lei Tao/Rice University.Bumpy diamond surfaces covered with graphene could help to dissipate heat in next-generation microelectronic devices, according to scientists at Rice University.
Their theoretical studies show that enhancing the interface between gallium nitride semiconductors and diamond heat sinks would allow phonons – quasiparticles of sound that also carry heat – to disperse more efficiently. Heat sinks are used to carry heat away from electronic devices.
In computer models, Rice materials scientist Rouzbeh Shahsavari and his colleagues tried replacing the flat interface between the materials with a nanostructured pattern and then added a layer of graphene, the atom-thick form of carbon, as a way to improve heat transfer. This new work by Shahsavari, Rice graduate student Lei Tao and postdoctoral researcher Sreeprasad Sreenivasan is reported in a paper ACS Applied Materials and Interfaces.
No matter the size, electronic devices need to disperse the heat they produce, Shahsavari said. “With the current trend of constant increases in power and device miniaturization, efficient heat management has become a serious issue for reliability and performance,” he explained. “Oftentimes, the individual materials in hybrid nano- and microelectronic devices function well but the interface of different materials is the bottleneck for heat diffusion.”
Gallium nitride has become a strong candidate for use in high-power, high-temperature applications like uninterruptible power supplies, motors, solar converters and hybrid vehicles. Diamond, meanwhile, is an excellent heat sink, but phonons struggle to traverse its atomic interface with gallium nitride.
To improve the situation, the researchers simulated 48 distinct grid patterns with square or round graphene pillars and tuned them to match phonon vibration frequencies between the materials. They found that a dense pattern of small squares on the surface of the diamond led to a dramatic decrease in the thermal boundary resistance of up to 80%. Adding a layer of graphene between the materials further reduced resistance by 33%.
Fine-tuning the length, size, shape, hierarchy, density and order of the pillars will be important, Lei said. “With current and emerging advancements in nanofabrication like nanolithography, it is now possible to go beyond the conventional planer interfaces and create strategically patterned interfaces coated with nanomaterials to significantly boost heat transport,” Shahsavari said. “Our strategy is amenable to several other hybrid materials and provides novel insights to overcome the thermal boundary resistance bottleneck.”
This story is adapted from material from Rice University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.