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Proceedings Paper

Quantum interference in EGaIn based tunneling junctions
Author(s): Davide Fracasso; Ryan C. Chiechi
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Paper Abstract

In this report we discuss the great potential of Eutectic Gallium Indium (EGaIn) as conformal soft top electrode. EGaIn is a liquid eutectic supporting a skin (∼ 1 nm-thick) of self-limiting oxide Ga2O3 as a non-damaging, conformal top-contact. In the last half of decade EGaIn has been used by several group to form molecular junctions and study charge transport properties in self-assembled monolayer (SAMs). We compared the current density (J) versus applied bias (V) for three different self-assembled monolayers (SAMs) of ethynylthiophenol- functionalized anthracene derivatives with approximately the same thickness and diverse conjugation: linear- conjugation (AC), cross-conjugation (AQ), and broken-conjugation (AH) by using liquid eutectic Ga-In (EGaIn). This skin imparts non-Newtonian rheological properties that distinguish EGaIn from other top-contacts, however it may also have limited the maximum values of J observed for AC. We measure values of J for AH and AQ which are not significantly different (J ≈ 10-1 A/cm2 at V = 0.4 V). For AC, however, J is one (using log-averages) or two (using Gaussian mean) orders of magnitude higher than both AH and AQ. Our results are also in good qualitative agreement with gDFTB calculations on single AC, AQ, and AH molecules transport calculation, based on chemisorbed between Au contacts which predict currents, I, that are two orders of magnitude higher for AC than AH at 0 < |V| < 0.4 V. We ascribe these observations to quantum-interference effects. The agreement between the theoretical predictions on single-molecules and the measurements on SAMs suggest that molecule-molecule interactions do not play a significant role in the transport properties of AC, AQ, and AH.

Paper Details

Date Published: 11 September 2013
PDF: 13 pages
Proc. SPIE 8811, Physical Chemistry of Interfaces and Nanomaterials XII, 88110U (11 September 2013); doi: 10.1117/12.2026174
Show Author Affiliations
Davide Fracasso, Univ. of Groningen (Netherlands)
Ryan C. Chiechi, Univ. of Groningen (Netherlands)

Published in SPIE Proceedings Vol. 8811:
Physical Chemistry of Interfaces and Nanomaterials XII
Natalie Banerji; Carlos Silva, Editor(s)

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