Department of Chemistry, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom.
H. H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
Nano Lett. 2017 Feb 8;17(2):1109-1115. doi: 10.1021/acs.nanolett.6b04663. Epub 2017 Jan 18.
In most single- or few-molecule devices, the contact electrodes are simple ohmic resistors. Here we describe a new type of single-molecule device in which metal and semiconductor contact electrodes impart a function, namely, current rectification, which is then modified by a molecule bridging the gap. We study junctions with the structure Au STM tip/X/n-GaAs substrate, where "X" is either a simple alkanedithiol or a conjugated unit bearing thiol/methylthiol contacts, and we detect current jumps corresponding to the attachment and detachment of single molecules. From the magnitudes of the current jumps we can deduce values for the conductance decay constant with molecule length that agree well with values determined from Au/molecule/Au junctions. The ability to impart functionality to a single-molecule device through the properties of the contacts as well as through the properties of the molecule represents a significant extension of the single-molecule electronics "tool-box".
在大多数单分子或少数分子器件中，接触电极是简单的欧姆电阻器。在这里，我们描述了一种新型的单分子器件，其中金属和半导体接触电极赋予了一种功能，即电流整流，然后通过桥接间隙的分子来修饰该功能。我们研究了具有结构 Au STM 尖端/X/n-GaAs 衬底的结，其中“X”是简单的烷二硫醇或带有硫醇/甲基硫醇接触的共轭单元，并且我们检测到对应于单个分子附着和脱附的电流跃变。从电流跃变的幅度，我们可以推断出与通过 Au/分子/Au 结确定的值相吻合的分子长度的电导衰减常数的值。通过接触的性质以及通过分子的性质赋予单分子器件功能的能力，代表了单分子电子学“工具箱”的重要扩展。
