Exceptional ballistic transport in epitaxial graphene nanoribbons
Exceptional ballistic transport in epitaxial graphene nanoribbons
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DOI：
10.1038/nature12952
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发表时间：
2014-02-20
期刊：
影响因子：
64.8
通讯作者：
de Heer, Walt A.
中科院分区：
文献类型：
--
作者：
Baringhaus, Jens;Ruan, Ming;de Heer, Walt A.
石墨烯纳米带将成为未来石墨烯纳米电子学的重要组成部分(1)。然而，在由光刻图案化剥离石墨烯生产的典型纳米带中，载流子在散射事件之间仅行进约十纳米，导致最小薄层电阻约为每平方千欧姆(2-5)。在这里，我们证明了在碳化硅（6,7）上外延生长的40纳米宽的石墨烯纳米带是长度大于10微米的单通道室温弹道导体，这与金属碳纳米管的性能相似。这相当于每平方低于 1 欧姆的薄层电阻，比完美石墨烯 (8) 的理论预测至少高出一个数量级。在中性石墨烯带中，我们表明传输主要由两种模式决定。其一是与弹道和温度无关的；另一个是热激活的。传输受到保护，免受反向散射，这可能反映了中性石墨烯的基态特性。在室温下，两种模式的电阻被发现在特定长度处突然增加——弹道模式在 16 微米，另一种在 160 纳米。我们的外延石墨烯纳米带不仅在基础科学中很重要，而且因为它们可以很容易地在数千个先进的纳米电子器件中生产，这些纳米电子器件可以利用它们的室温弹道传输特性。
Graphene nanoribbons will be essential components in future graphene nanoelectronics(1). However, in typical nanoribbons produced from lithographically patterned exfoliated graphene, the charge carriers travel only about ten nanometres between scattering events, resulting in minimum sheet resistances of about one kilohm per square(2-5). Here we show that 40-nanometre-wide graphene nanoribbons epitaxially grown on silicon carbide(6,7) are single-channel room-temperature ballistic conductors on a length scale greater than ten micrometres, which is similar to the performance of metallic carbon nanotubes. This is equivalent to sheet resistances below 1 ohm per square, surpassing theoretical predictions for perfect graphene(8) by at least an order of magnitude. In neutral graphene ribbons, we show that transport is dominated by two modes. One is ballistic and temperature independent; the other is thermally activated. Transport is protected from back-scattering, possibly reflecting ground-state properties of neutral graphene. At room temperature, the resistance of both modes is found to increase abruptly at a particular length-the ballistic mode at 16 micrometres and the other at 160 nanometres. Our epitaxial graphene nanoribbons will be important not only in fundamental science, but also-because they can be readily produced in thousands-in advanced nanoelectronics, which can make use of their room-temperature ballistic transport properties.