Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, University of California, Riverside, California 92521, USA.
Nano Lett. 2012 Mar 14;12(3):1603-8. doi: 10.1021/nl204545q. Epub 2012 Feb 15.
Graphene demonstrated potential for practical applications owing to its excellent electronic and thermal properties. Typical graphene field-effect transistors and interconnects built on conventional SiO(2)/Si substrates reveal the breakdown current density on the order of 1 μA/nm(2) (i.e., 10(8) A/cm(2)), which is ~100× larger than the fundamental limit for the metals but still smaller than the maximum achieved in carbon nanotubes. We show that by replacing SiO(2) with synthetic diamond, one can substantially increase the current-carrying capacity of graphene to as high as ~18 μA/nm(2) even at ambient conditions. Our results indicate that graphene's current-induced breakdown is thermally activated. We also found that the current carrying capacity of graphene can be improved not only on the single-crystal diamond substrates but also on an inexpensive ultrananocrystalline diamond, which can be produced in a process compatible with a conventional Si technology. The latter was attributed to the decreased thermal resistance of the ultrananocrystalline diamond layer at elevated temperatures. The obtained results are important for graphene's applications in high-frequency transistors, interconnects, and transparent electrodes and can lead to the new planar sp(2)-on-sp(3) carbon-on-carbon technology.
由于其优异的电子和热性能，石墨烯在实际应用中具有很大的潜力。在传统的 SiO(2)/Si 衬底上构建的典型石墨烯场效应晶体管和互连，其击穿电流密度约为 1 μA/nm(2)（即 10(8) A/cm(2)），这比金属的基本极限大100 倍，但仍小于在碳纳米管中实现的最大值。我们表明，通过用合成金刚石代替 SiO(2)，即使在环境条件下，也可以将石墨烯的载流能力显著提高到高达18 μA/nm(2)。我们的结果表明，石墨烯的电流诱导击穿是热激活的。我们还发现，不仅在单晶金刚石衬底上，而且在廉价的超细纳米金刚石上，也可以提高石墨烯的载流能力，而超细纳米金刚石可以在与传统 Si 技术兼容的工艺中生产。后者归因于在高温下超细纳米金刚石层的热阻降低。所得结果对于石墨烯在高频晶体管、互连和透明电极中的应用非常重要，并可能导致新的平面 sp(2)-on-sp(3) 碳-碳技术的出现。
