Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS - Université de Strasbourg), 67034 Strasbourg, France.
Nat Nanotechnol. 2011 Jan;6(1):23-7. doi: 10.1038/nnano.2010.215. Epub 2010 Nov 14.
The transport of charge through a conducting material depends on the intrinsic ability of the material to conduct current and on the charge injection efficiency at the contacts between the conductor and the electrodes carrying current to and from the material. According to theoretical considerations, this concept remains valid down to the limit of single-molecule junctions. Exploring this limit in experiments requires atomic-scale control of the junction geometry. Here we present a method for probing the current through a single C(60) molecule while changing, one by one, the number of atoms in the electrode that are in contact with the molecule. We show quantitatively that the contact geometry has a strong influence on the conductance. We also find a crossover from a regime in which the conductance is limited by charge injection at the contact to a regime in which the conductance is limited by scattering at the molecule. Thus, the concepts of 'good' and 'bad' contacts, commonly used in macro- and mesoscopic physics, can also be applied at the molecular scale.
电荷通过导体的传输取决于材料本身传导电流的能力，以及在导体与电极之间的接触处的电荷注入效率，电极将电流输入和输出到材料中。根据理论考虑，这个概念在单分子结的极限下仍然有效。在实验中探索这个极限需要原子尺度上对结几何形状的控制。在这里，我们提出了一种方法，用于在改变与分子接触的电极中的原子数量的同时，探测单个 C(60)分子中的电流。我们定量地表明，接触几何形状对电导有很大的影响。我们还发现，从电导受到接触处电荷注入限制的区域到电导受到分子散射限制的区域发生了转变。因此，在宏观和介观物理中常用的“好”和“坏”接触的概念也可以应用于分子尺度。
