Trilayer graphene is a semimetal with a gate-tunable band overlap
Trilayer graphene is a semimetal with a gate-tunable band overlap
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DOI：
10.1038/nnano.2009.89
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发表时间：
2009-06-01
影响因子：
38.3
通讯作者：
Tarucha, S.
中科院分区：
文献类型：
--
作者：
Craciun, M. F.;Russo, S.;Tarucha, S.
基于石墨烯的材料是纳米电子器件很有前景的候选材料（1 - 14），因为无需使用复杂的材料制备技术就可实现很高的载流子迁移率（1）。然而，据报道，单层和双层石墨烯的载流子迁移率仍然低于低温下石墨晶体的载流子迁移率，并且对于任何给定应用而言，石墨烯的最佳层数目前尚不清楚，因为包含三层或更多层石墨烯的样品的电荷传输特性尚未得到系统研究（1）。在此，我们研究了作为载流子密度、温度和垂直电场函数的三层石墨烯中的电荷传输。我们发现三层石墨烯是一种电阻率随电场增加而降低的半金属，这种行为与单层和双层石墨烯的行为明显不同。我们表明这种现象源于可由电场控制的导带和价带之间的重叠，这是一种此前在任何其他半金属中从未观察到的特性。我们还确定了电荷载流子的有效质量，并表明当样品中的层数变化时，它在载流子迁移率的变化中占很大一部分。
Graphene-based materials are promising candidates for nanoelectronic devices(1-14) because very high carrier mobilities can be achieved without the use of sophisticated material preparation techniques(1). However, the carrier mobilities reported for single-layer and bilayer graphene are still less than those reported for graphite crystals at low temperatures, and the optimum number of graphene layers for any given application is currently unclear, because the charge transport properties of samples containing three or more graphene layers have not yet been investigated systematically(1). Here, we study charge transport through trilayer graphene as a function of carrier density, temperature, and perpendicular electric field. We find that trilayer graphene is a semimetal with a resistivity that decreases with increasing electric field, a behaviour that is markedly different from that of single-layer and bilayer graphene. We show that the phenomenon originates from an overlap between the conduction and valence bands that can be controlled by an electric field, a property that had never previously been observed in any other semimetal. We also determine the effective mass of the charge carriers, and show that it accounts for a large part of the variation in the carrier mobility as the number of layers in the sample is varied.