A University
of California, Riverside (UC Riverside) engineering
professor and a team of researchers have made a breakthrough discovery with
graphene, a material that could play a major role in keeping laptops and other
electronic devices from overheating.
Alexander Balandin, a professor of
electrical engineering at the UC Riverside Bourns College of Engineering, and
researchers from The University of Texas at Austin,
The University of Texas at Dallas, and Xiamen University
in China,
have shown that the thermal properties of isotopically engineered graphene are
far superior to those of graphene in its natural state.
The research efforts were led by the
Professor Rodney S. Ruoff of UT Austin and Balandin, a corresponding author for
the paper, “Thermal conductivity of isotopically modified graphene.” It was
published online in Nature Materials.
The results bring graphene one step closer
to being used as a thermal conductor for managing heat dissipation in
everything from electronics to photovoltaic solar cells to radars.
“The important finding is the possibility
of a strong enhancement of thermal conduction properties of isotopically pure
graphene without substantial alteration of electrical, optical and other
physical properties,” Balandin said. “Isotopically pure graphene can become an
excellent choice for many practical applications provided that the cost of the
material is kept under control.”
He added: “The experimental data on heat
conduction in isotopically engineered graphene is also crucially important for
developing an accurate theory of thermal conductivity in graphene and other 2D
crystals.”
The research used the optothermal Raman
method, a thermal conductivity measuring technique developed by Balandin. In
2008, Balandin and his group members demonstrated experimentally that graphene
is an excellent heat conductor. They also developed the first detailed theory
of heat conduction in graphene and related 2D crystals.
The work presented in the Nature Materials paper shows that the
thermal conductivity of isotopically engineered graphene is strongly enhanced
compared to graphene in its natural state.
Naturally occurring carbon materials,
including graphene, are made up of two stable isotopes—about 99% of 12C
(referred to as carbon 12) and 1% of 13C (referred to as carbon 13). The
difference between isotopes is in the atomic mass of the carbon atoms. The removal
of just about 1% of carbon 13, also called isotopic purification, modifies the
dynamic properties of crystal lattices and affects their thermal conductivity.
The importance of the present research is
explained by practical needs for materials with high thermal conductivity. Heat
removal has become a crucial issue for continuing progress in the electronics
industry, owing to increased levels of dissipated power as the devices become
smaller and smaller. The search for materials that conduct heat well has become
essential for the design of the next generation of integrated circuits and 3D
electronics.
Balandin, who is also founding chair of the
materials science and engineering (MS&E) program at UC Riverside, believes
graphene will gradually be incorporated into different devices.
Intially, it will likely be used in some
niche applications such as thermal interface materials for chip packaging or
transparent electrodes in photovoltaic solar cells or flexible displays, he
said.
In a few years, it could be used with
silicon in computer chips, for example as interconnect wiring or heat
spreaders. It also has the potential to benefit other electronic applications,
including analog high-frequency transistors, which are used in wireless
communications, radar, security systems, and imaging.
