Shot Noise of 1,4-Benzenedithiol Single-Molecule Junctions

• Published in: Nano letters Vol. 16; no. 3; pp. 1803 - 1807
• Main Authors: Karimi, M. A, Bahoosh, S. G, Herz, M, Hayakawa, R, Pauly, F, Scheer, E
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.03.2016
• Subjects: Analyzers; Channels; Charge transport; Conductance; Density functional theory; Electrical junctions; Mathematical analysis; Shot noise; shot noise; inelastic electron tunneling spectroscopy; Single-molecule junction; low temperature; charge transport; density functional theory
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.5b04848

We report measurements of the shot noise on single-molecule Au–1,4-benzenedithiol–Au junctions, fabricated with the mechanically controllable break junction (MCBJ) technique at 4.2 K in a wide range of conductance values from 10–2 to 0.24 conductance quanta. We introduce a simple measurement scheme using a current amplifier and a spectrum analyzer and that does not imply special requirements regarding the electrical leads. The experimental findings provide evidence that the current is carried by a single conduction channel throughout the whole conductance range. This observation suggests that the number of channels is limited by the Au-thiol bonds and that contributions due to direct tunneling from the Au to the π-system of the aromatic ring are negligible also for high conductance. The results are supported by quantum transport calculations using density functional theory.