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'Hot' Graphene May Finally Cool Down Electronics

by Editor1 last modified May 10, 2010 - 21:55

University of California (Riverside) researchers may have taken the next giant step in using graphene for new heat-resisting materials to keep laptops and other electronic devices from overheating. The key is a new graphene structure that is less expensive and easier to produce, and that can be incorporated with silicon.

'Hot' Graphene May Finally Cool Down Electronics

Prof. Alexander Balandin, chair of University of California Riverside’s Material Sciences and Engineering program

The work was led by Prof. Alexander Balandin, a professor of electrical engineering in the Bourns College of Engineering, and Chun Ning Lau, an associate professor of physics.

In 2008, Balandin’s team demonstrated graphene has strong heat-conductor properties, but it was difficult to produce large, high-quality single atomic layers of the material. Now, Balandin and co-workers has found multiple layers of graphene, which are easier to make than single-atom layers, also exhibit strong heat conducting properties.

Balandin's group explained theoretically how the materials' ability to conduct heat evolves when one goes from conventional three-dimensional bulk materials to two-dimensional atomically-thin films, such as graphene.

The results published in Nature Materials may have important practical applications in removal of dissipated hear from electronic devices.

Why Graphene is so 'Hot' Among Electronics Professionals
Heat is an unavoidable by-product when operating electronic devices.

Electronic circuits contain many sources of heat, including millions of transistors and interconnecting wiring. In the past, fans have been used to keep computer chips cool, important to on-going operations and long product life. However, fans are reaching the end of their usefulness for dispersing heat as computers get faster and other chip-based electronics, such as cellphones and PDAs, get smaller.

So, attention is turning to find ways to incorporate novel materials with superior thermal properties, such as graphene, into silicon computer chips. While silicon has good electronic properties it’s not so good at dealing with heat build-ups, particularly when structured at the nanometer scale, Balandin said. As Balandin's research shows, graphene has excellent thermal properties in addition to unique electronic characteristics.

"Graphene is one of the hottest materials right now," said Balandin, who is also chair of UC Riverside’s Material Sciences and Engineering program. Because graphene can now exhibit heat-resistant qualities in thicker layers, it could be used in conjunction with silicon, he added. At this point, there is no reliable way to synthesize large quantities of graphene. However, progress is being made and it could be possible in a year or two, Balandin said.

Initially, graphene would likely be used in some niche applications such as thermal interface materials for chip packaging or transparent electrodes in photovoltaic solar cells, Balandin said. But, in five years, he said, it could be used with silicon in computer chips, for example as interconnect wiring or heat spreaders. It may also find applications in ultra-fast transistors for radio frequency communications. Low-noise graphene transistors have already been demonstrated in Balandin's lab.

Balandin published the Nature Materials paper with two of his graduate students Suchismita Ghosh, who is now at Intel Corp., and Samia Subrina, Lau. one of her graduate students, Wenzhong Bao, and Denis L. Nika and Evghenii P. Pokatilov, visting researchers in Balandin's lab who are based at the State University of Moldova.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of over 19,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.