Department of Chemistry, Stanford University, Stanford, California 94305, USA.
Nat Nanotechnol. 2011 Aug 28;6(9):563-7. doi: 10.1038/nnano.2011.138.
Graphene nanoribbons with perfect edges are predicted to exhibit interesting electronic and spintronic properties, notably quantum-confined bandgaps and magnetic edge states. However, so far, graphene nanoribbons produced by lithography have had rough edges, as well as low-temperature transport characteristics dominated by defects (mainly variable range hopping between localized states in a transport gap near the Dirac point). Here, we report that one- and two-layer nanoribbon quantum dots made by unzipping carbon nanotubes exhibit well-defined quantum transport phenomena, including Coulomb blockade, the Kondo effect, clear excited states up to ∼20 meV, and inelastic co-tunnelling. Together with the signatures of intrinsic quantum-confined bandgaps and high conductivities, our data indicate that the nanoribbons behave as clean quantum wires at low temperatures, and are not dominated by defects.
具有完美边缘的石墨烯纳米带被预测将表现出有趣的电子和自旋电子特性，特别是量子受限的能带隙和磁性边缘态。然而，到目前为止，通过光刻生产的石墨烯纳米带具有粗糙的边缘，以及低温输运特性由缺陷主导（主要是在狄拉克点附近的输运间隙中局域态之间的可变范围跳跃）。在这里，我们报告了通过解开碳纳米管制成的单层和双层纳米带量子点表现出明确的量子输运现象，包括库仑阻塞、Kondo 效应、高达约 20 meV 的清晰激发态以及非弹性共隧道。与内在量子受限能带隙和高电导率的特征一起，我们的数据表明纳米带在低温下表现为清洁的量子线，而不是由缺陷主导。
