Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Nano Lett. 2010 Sep 8;10(9):3611-9. doi: 10.1021/nl101918m.
This paper describes a method of fabrication that generates small arrays of tunneling junctions based on self-assembled monolayers (SAMs); these junctions have liquid-metal top-electrodes stabilized in microchannels and ultraflat (template-stripped) bottom-electrodes. The yield of junctions generated using this method is high (70-90%). The junctions examined incorporated SAMs of alkanethiolates having ferrocene termini (11-(ferrocenyl)-1-undecanethiol, SC(11)Fc); these junctions rectify currents with large rectification ratios (R), the majority of which fall within the range of 90-180. These values are larger than expected (theory predicts R <or= 20) and are larger than previous experimental measurements. SAMs of n-alkanethiolates without the Fc groups (SC(n-1)CH(3), with n = 12, 14, 16, or 18) do not rectify (R ranged from 1.0 to 5.0). These arrays enable the measurement of the electrical characteristics of the junctions as a function of chemical structure, voltage, and temperature over the range of 110-293 K, with statistically large numbers of data (N = 300-800). The mechanism of rectification with Fc-terminated SAMs seems to be charge transport processes that change with the polarity of bias: from tunneling (at one bias) to hopping combined with tunneling (at the opposite bias).
本文描述了一种基于自组装单分子层（SAMs）生成隧道结小阵列的制造方法；这些结具有稳定在微通道中的液态金属顶电极和超平（模板剥离）底电极。使用这种方法生成的结的产率很高（70-90%）。检查的结包含具有二茂铁末端的烷硫醇 SAM（11-（二茂铁基）-1-十一硫醇，SC（11）Fc）；这些结具有大整流比（R）的电流整流，其中大多数落在 90-180 范围内。这些值大于预期（理论预测 R <或= 20），并且大于以前的实验测量值。没有 Fc 基团的 n-烷硫醇 SAM（SC（n-1）CH（3），n = 12、14、16 或 18）不整流（R 范围为 1.0 至 5.0）。这些阵列允许测量结的电特性作为化学结构、电压和温度的函数，范围为 110-293 K，具有统计上大量的数据（N = 300-800）。具有 Fc 端 SAM 的整流机制似乎是随着偏置极性而变化的电荷传输过程：从隧道（在一个偏置）到隧穿结合跳跃（在相反偏置）。
