Faculty of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 252-5258, Japan.
Nat Nanotechnol. 2011 Jan;6(1):45-50. doi: 10.1038/nnano.2010.249. Epub 2010 Dec 19.
The usefulness of graphene for electronics has been limited because it does not have an energy bandgap. Although graphene nanoribbons have non-zero bandgaps, lithographic fabrication methods introduce defects that decouple the bandgap from electronic properties, compromising performance. Here we report direct measurements of a large intrinsic energy bandgap of approximately 50 meV in nanoribbons (width, approximately 100 nm) fabricated by high-temperature hydrogen-annealing of unzipped carbon nanotubes. The thermal energy required to promote a charge to the conduction band (the activation energy) is measured to be seven times greater than in lithographically defined nanoribbons, and is close to the width of the voltage range over which differential conductance is zero (the transport gap). This similarity suggests that the activation energy is in fact the intrinsic energy bandgap. High-resolution transmission electron and Raman microscopy, in combination with an absence of hopping conductance and stochastic charging effects, suggest a low defect density.
石墨烯在电子学方面的应用受到限制，因为它没有能隙。尽管石墨烯纳米带具有非零带隙，但光刻制造方法会引入缺陷，从而使带隙与电子性质解耦，从而影响性能。在这里，我们报告了通过高温氢气退火解扭的碳纳米管直接测量约 50meV 的大固有能隙的结果。在由光刻定义的纳米带中，促进电荷进入导带所需的热能（激活能）要大 7 倍，并且接近微分电导为零的电压范围（传输间隙）的宽度。这种相似性表明，激活能实际上就是固有能隙。高分辨率透射电子显微镜和拉曼显微镜，结合不存在跳跃电导和随机充电效应，表明缺陷密度较低。
