Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 53, 20125 Milano, Italy.
Phys Chem Chem Phys. 2012 Aug 14;14(30):10683-9. doi: 10.1039/c2cp40702g. Epub 2012 Jun 28.
The transmission properties of armchair graphene nanoribbon junctions between graphene electrodes are investigated by means of first-principles quantum transport calculations. First the dependence of the transmission function on the size of the nanoribbon has been studied. Two regimes are highlighted: for a small applied bias transport takes place via tunneling and the length of the ribbon is the key parameter that determines the junction conductance; at a higher applied bias resonant transport through the HOMO and LUMO starts to play a more determinant role, and the transport properties depend on the details of the geometry (width and length) of the carbon nanoribbon. In the case of the thinnest ribbon it has been verified that a tilted geometry of the central phenyl ring is the most stable configuration. As a consequence of this rotation the conductance decreases due to the misalignment of the π orbitals between the phenyl ring and the remaining part of the junction. All the computed transmission functions have shown a negligible dependence on different saturations and reconstructions of the edges of the graphene leads, suggesting a general validity of the reported results.
通过第一性原理量子输运计算，研究了石墨烯电极之间扶手椅型石墨烯纳米带结的传输特性。首先研究了传输函数对纳米带大小的依赖性。突出了两种情况：对于较小的施加偏压，通过隧道进行传输，并且纳米带的长度是决定结电导率的关键参数；在更高的施加偏压下，通过 HOMO 和 LUMO 的共振传输开始发挥更决定性的作用，并且传输特性取决于碳纳米带的几何形状（宽度和长度）的细节。在最薄的纳米带的情况下，已经验证了中央苯基环的倾斜几何形状是最稳定的构型。由于这种旋转，由于苯环和结的其余部分之间的π轨道不对准，电导减小。所有计算的传输函数都显示出对不同的石墨烯引导边缘的饱和和重构的微不足道的依赖性，这表明所报道的结果具有普遍的有效性。
