MMaterialsgateNEWS 2016/12/01

Related MaterialsgateCARDS

Electronics: Bumpy surfaces, graphene beat the heat in devices

Credit: Lei Tao/Rice University

Rice University theory shows way to enhance heat sinks in future microelectronics

Bumpy surfaces with graphene between would help dissipate heat in next-generation microelectronic devices, according to Rice University scientists.

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.

Rice computer models replaced the flat interface between the materials with a nanostructured pattern and added a layer of graphene, the atom-thick form of carbon, as a way to dramatically improve heat transfer, said Rice materials scientist Rouzbeh Shahsavari.

The new work by Shahsavari, Rice graduate student and lead author Lei Tao and postdoctoral researcher Sreeprasad Sreenivasan appeared this month in the American Chemical Society journal 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 said. "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, he said. Diamond is an excellent heat sink, but its atomic interface with gallium nitride is hard for phonons to traverse.

The researchers simulated 48 distinct grid patterns with square or round graphene pillars and tuned them to match phonon vibration frequencies between the materials. Sinking a dense pattern of small squares into the diamond showed a dramatic decrease in thermal boundary resistance of up to 80 percent. A layer of graphene between the materials further reduced resistance by 33 percent.

Fine-tuning the pillar length, size, shape, hierarchy, density and order 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."

Shahsavari is an assistant professor of civil and environmental engineering and of materials science and nanoengineering.

The researchers used the Blue Gene supercomputer and the National Science Foundation-supported DAVinCI supercomputer, which are both administered by Rice's Center for Research Computing and were procured in partnership with Rice's Ken Kennedy Institute for Information Technology.

Source: Rice University – 29.11.2016.

Investigated and edited by:

Dr.-Ing. Christoph Konetschny, Inhaber und Gründer von Materialsgate
Büro für Material- und Technologieberatung
The investigation and editing of this document was performed with best care and attention.
For the accuracy, validity, availability and applicability of the given information, we take no liability.
Please discuss the suitability concerning your specific application with the experts of the named company or organization.

You want additional material or technology investigations concerning this subject?

Materialsgate is leading in material consulting and material investigation.
Feel free to use our established consulting services

MMore on this topic

Credit: S.K. Yoon, Korea University

A new, ultrathin film that is both transparent and highly conductive to electric current has been produced by a cheap and simple method devised by an international team of nanomaterials researchers from the University of Illinois at Chicago and Korea University.

The film is also bendable and stretchable, offering potential applications in roll-up touchscreen displays, wearable electronics, flexible solar cells and electronic skin. The results are reported in Advanced Functional Materials. The new film is made of fused silver nanowires, and is produced by spraying the nanowire particles through a tiny jet nozzle at supersonic speed. The result is a film with nearly the electrical conductivity of silver-plate -- and the transparency of glass, says senior author Alexander Yarin, UIC Distinguished Professor of Mechanical Engineering. "The silver nanowire is a particle, but very long and thin," Yarin said. The nanowires measure about 20 microns... more read more

Counterintuitive 'metamaterial' may enable heat-resistant circuit boards

Almost all solid materials, from rubber and glass to granite and steel, inevitably expand when heated. Only in very rare instances do certain materials buck this thermodynamic trend and shrink with heat. For instance, cold water will contract when heated between 0 and 4 degrees Celsius, before expanding. Engineers from MIT, the University of Southern California, and elsewhere are now adding to this curious class of heat-shrinking materials. The team, led by Nicholas X. Fang, an associate professor of mechanical engineering at MIT, has manufactured tiny, star-shaped structures out of interconnected beams, or trusses. The structures, each about the size of a sugar cube, quickly shrink when... more read more

Credit: Zhuhua Zhang/Rice University

Though they're touted as ideal for electronics, two-dimensional materials like graphene may be too flat and hard to stretch to serve in flexible, wearable devices. "Wavy" borophene might be better, according to Rice University scientists.

The Rice lab of theoretical physicist Boris Yakobson and experimental collaborators observed examples of naturally undulating, metallic borophene, an atom-thick layer of boron, and suggested that transferring it onto an elastic surface would preserve the material's stretchability along with its useful electronic properties. Highly conductive graphene has promise for flexible electronics, Yakobson said, but it is too stiff for devices that also need to stretch, compress or even twist. But borophene deposited on a silver substrate develops nanoscale corrugations. Weakly bound to the silver, it could be moved to a flexible surface for use. The research appears this month in the American... more read more

Credit: Stephanie Precourt

For decades, scientists have tried to harness the unique properties of carbon nanotubes to create high-performance electronics that are faster or consume less power -- resulting in longer battery life, faster wireless communication and faster processing speeds for devices like smartphones and laptops.

But a number of challenges have impeded the development of high-performance transistors made of carbon nanotubes, tiny cylinders made of carbon just one atom thick. Consequently, their performance has lagged far behind semiconductors such as silicon and gallium arsenide used in computer chips and personal electronics. Now, for the first time, University of Wisconsin-Madison materials engineers have created carbon nanotube transistors that outperform state-of-the-art silicon transistors. Led by Michael Arnold and Padma Gopalan, UW-Madison professors of materials science and engineering, the team's carbon nanotube transistors achieved current that's 1.9 times higher than silicon... more read more

MaterialsgateNEWSLETTER

Partner of the Week

Search in MaterialsgateNEWS

Books and products

MaterialsgateFAIR:
LET YOURSELF BE INSPIRED