Observation of electron-hole puddles in graphene using a scanning single-electron transistor
Observation of electron-hole puddles in graphene using a scanning single-electron transistor
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DOI：
10.1038/nphys781
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发表时间：
2008-02-01
期刊：
影响因子：
19.6
通讯作者：
Yacoby, A.
中科院分区：
文献类型：
--
作者：
Martin, J.;Akerman, N.;Yacoby, A.
石墨烯的电子结构使其电荷载体表现得像相对论粒子。对于没有杂质和无序的完美石墨烯片，费米能位于所谓的“狄拉克点”，在那里电子态密度为零。但是，在无序不可避免的情况下，理论预测，同样可能出现富含电子和空穴的水坑区域。这些水坑可以解释石墨烯在零平均载流子密度下的异常非零最小电导率。在这里，我们使用扫描单电子晶体管来映射中性点附近的局域态密度和载流子密度分布。我们的研究结果证实了电子空穴水坑的存在，并排除了非本征衬底效应作为其出现和拓扑结构的解释。此外，我们发现，不像非相对论粒子的状态密度可以定量占考虑非相互作用的电子和空穴。
The electronic structure of graphene causes its charge carriers to behave like relativistic particles. For a perfect graphene sheet free from impurities and disorder, the Fermi energy lies at the so-called 'Dirac point', where the density of electronic states vanishes. But in the inevitable presence of disorder, theory predicts that equally probable regions of electron-rich and hole-rich puddles will arise. These puddles could explain graphene's anomalous non-zero minimal conductivity at zero average carrier density. Here, we use a scanning single-electron transistor to map the local density of states and the carrier density landscape in the vicinity of the neutrality point. Our results confirm the existence of electron-hole puddles, and rule out extrinsic substrate effects as explanations for their emergence and topology. Moreover, we find that, unlike non-relativistic particles the density of states can be quantitatively accounted for by considering non-interacting electrons and holes.