Approaching ballistic transport in suspended graphene
Approaching ballistic transport in suspended graphene
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DOI：
10.1038/nnano.2008.199
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发表时间：
2008-08-01
影响因子：
38.3
通讯作者：
Andrei, Eva Y.
中科院分区：
文献类型：
--
作者：
Du, Xu;Skachko, Ivan;Andrei, Eva Y.
石墨烯（1，2）的发现提升了一种新型纳米电子器件的前景，这种纳米电子器件基于这种单原子厚的碳层的非凡物理特性（3-6）。与半导体中的二维电子层不同，其中电荷载流子在低密度下变得不动，石墨烯中的载流子迁移率可以保持很高，即使它们的密度在狄拉克点处消失。然而，当石墨烯样品被支撑在绝缘衬底上时，电势波动会引起模糊狄拉克点物理的电荷池。在这里，我们表明悬浮石墨烯样品中的波动显着减少，并且我们报告说，对于低于5 x 10（9）cm（-2）的载流子密度，低温迁移率接近200，000 cm（2）V-1 s（-1）。在半导体或非悬浮石墨烯中无法获得这样的值。此外，与由衬底支撑的石墨烯样品不同，悬浮石墨烯在狄拉克点处的电导率强烈依赖于温度，并且在液氦温度下接近弹道值。在较高的温度下，高于100 K，我们观察到热致长程散射的发病。
The discovery of graphene(1,2) raises the prospect of a new class of nanoelectronic devices based on the extraordinary physical properties(3-6) of this one-atom-thick layer of carbon. Unlike two-dimensional electron layers in semiconductors, where the charge carriers become immobile at low densities, the carrier mobility in graphene can remain high, even when their density vanishes at the Dirac point. However, when the graphene sample is supported on an insulating substrate, potential fluctuations induce charge puddles that obscure the Dirac point physics. Here we show that the fluctuations are significantly reduced in suspended graphene samples and we report low-temperature mobility approaching 200,000 cm(2) V-1 s(-1) for carrier densities below 5 x 10(9) cm(-2). Such values cannot be attained in semiconductors or non-suspended graphene. Moreover, unlike graphene samples supported by a substrate, the conductivity of suspended graphene at the Dirac point is strongly dependent on temperature and approaches ballistic values at liquid helium temperatures. At higher temperatures, above 100 K, we observe the onset of thermally induced long-range scattering.