Wan Albert, Suchand Sangeeth C S, Wang Lejia, Yuan Li, Jiang Li, Nijhuis Christian A
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Nanoscale. 2015 Dec 14;7(46):19547-56. doi: 10.1039/c5nr05533d.
This paper describes a method to fabricate a microfluidic top-electrode that can be utilized to generate arrays of self-assembled monolayer (SAM)-based junctions. The top-electrodes consist of a liquid-metal of GaOx/EGaIn mechanically stabilized in microchannels and through-holes in polydimethylsiloxane (PDMS); these top-electrodes form molecular junctions by directly placing them onto the SAM supported by template-stripped (TS) Ag or Au bottom-electrodes. Unlike conventional techniques to form multiple junctions, our method does not require lithography to pattern the bottom-electrode and is compatible with TS bottom-electrodes, which are ultra-flat with large grains, free from potential contamination of photoresist residues, and do not have electrode-edges where the molecules are unable to pack well. We formed tunneling junctions with n-alkanethiolate SAMs in yields of ∼80%, with good reproducibility and electrical stability. Temperature dependent J(V) measurements indicated that the mechanism of charge transport across the junction is coherent tunneling. To demonstrate the usefulness of these junctions, we formed molecular diodes based on SAMs with Fc head groups. These junctions rectify currents with a rectification ratio R of 45. These molecular diodes were incorporated in simple electronic circuitry to demonstrate molecular diode-based Boolean logic.
本文描述了一种制造微流控顶部电极的方法，该电极可用于生成基于自组装单分子层（SAM）的结阵列。顶部电极由机械稳定在微通道和聚二甲基硅氧烷（PDMS）通孔中的GaOx/EGaIn液态金属组成；这些顶部电极通过直接将它们放置在由模板剥离（TS）银或金底部电极支撑的SAM上形成分子结。与形成多个结的传统技术不同，我们的方法不需要光刻来对底部电极进行图案化，并且与TS底部电极兼容，TS底部电极超平且晶粒大，没有光刻胶残留的潜在污染，并且没有分子无法良好堆积的电极边缘。我们以约80%的产率形成了与正链烷硫醇盐SAM的隧道结，具有良好的重现性和电稳定性。温度依赖的J(V)测量表明，电荷通过结的传输机制是相干隧穿。为了证明这些结的有用性，我们基于带有Fc头基的SAM形成了分子二极管。这些结以45的整流比R整流电流。这些分子二极管被并入简单的电子电路中以展示基于分子二极管的布尔逻辑。
