Electrochemically Assisted Fabrication of Metal Atomic Wires and Molecular Junctions by MCBJ and STM‐BJ Methods

Abstract

Atomic wires (point contacts) and molecular junctions are two fundamental units in the fields of nanoelectronics and devices. This Minireview introduces our recent approaches aiming to develop versatile methods to fabricate and characterize these unique metallic and molecular structures reliably. Electrochemical methods are coupled with mechanically controllable break junction (EC-MCBJ) or scanning tunneling microscopy (STM) break junction (EC-STMBJ) methods to fabricate metallic point contacts and metal/molecule/metal junctions. With the designed electrodeposition method, the metal of interest (e.g. Au, Cu, Fe or Pd) is deposited in a controlled way on the original electrode pair, on a chip for MCBJ or on the STM tip, to make the metallic contact. Then, various metal atomic wires and molecular junctions can be fabricated and characterized systematically. Herein, we measured the quantized conductance through the construction of histograms of these metal atomic point contacts and of single molecules including benzene-1,4-dithiol (BDT), ferrocene-bisvinylphenylmethyl dithiol (Fc-VPM), 4,4'-bipyridine (BPY), 1,2-di(pyridin-4-yl)ethene (BPY-EE), and 1,2-di(pyridin-4-yl)ethane (BPY-EA). Finally, we briefly discussed the future of EC-MCBJ and EC-STM for nanoelectronics and devices, for example, for the formation of heterogeneous metal-based atomic point contacts and molecular junctions.

Single-Molecule Electronics: Chemical and Analytical Perspectives

“…The electrochemical gating of single molecules has been referred to as a single-molecule transistor configuration using analogies with field effect transistors. Electrochemical gating can be applied in the I(s) (29), the in situ break junction (13), and MCBJ (105,106) methods. The addition of a counter and reference electrode to the electrolyte solution and a bipotentiostat helps to control the electrochemical potential of both of the gold contacts independently.…”

Detecting Electron Transport of Amino Acids by Using Conductance Measurement

“…The break junction approach has been demonstrated to be an efficient method to measure the electron transport of molecular junctions [16,17,18,19,20,21]. In this article, we measure the conductance of amino acids by using an STM break junction [17,22,23,24,25,26,27].…”

Capturing electrochemical transformations by tip-enhanced Raman spectroscopy

“…Their exceptional performances allow to capture single atoms or molecules, to follow the structure evolution of a polarized interface [11,12] or to induce local surface alterations. [13] In addition to topographical features, they also give access to the conductivity of single molecules [14][15][16][17], to the local mechanical properties [18] or to the ionic transport properties in solids [19][20][21][22] among many other properties. Originating from near field microscopy, Scanning Electrochemical Microscopy (SECM) enables the control and the monitoring of the electron transfer properties at the micro/nanoscale.…”