Tunneling Characteristics of Au鈥揂lkanedithiol鈥揂u Junctions formed via Nanotransfer Printing (nTP)

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• 作者：Jeremy R. Niskala ; William C. Rice ; Robert C. Bruce ; Timothy J. Merkel ; Frank Tsui ; Wei You
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：July 25, 2012
• 年：2012
• 卷：134
• 期：29
• 页码：12072-12082
• 全文大小：637K
• 年卷期：v.134,no.29(July 25, 2012)
• ISSN：1520-5126

文摘

Construction of permanent metal鈥搈olecule鈥搈etal (MMM) junctions, though technically challenging, is desirable for both fundamental investigations and applications of molecule-based electronics. In this study, we employed the nanotransfer printing (nTP) technique using perfluoropolyether (PFPE) stamps to print Au thin films onto self-assembled monolayers (SAMs) of alkanedithiol formed on Au thin films. We show that the resulting MMM junctions form permanent and symmetrical tunnel junctions, without the need for an additional protection layer between the top metal electrode and the molecular layer. This type of junction makes it possible for direct investigations into the electrical properties of the molecules and the metal鈥搈olecule interfaces. Dependence of transport properties on the length of the alkane molecules and the area of the printed Au electrodes has been examined systematically. From the analysis of the current鈥搗oltage (I鈥揤) curves using the Simmons model, the height of tunneling barrier associated with the molecule (alkane) has been determined to be 3.5 卤 0.2 eV, while the analysis yielded an upper bound of 2.4 eV for the counterpart at the interface (thiol). The former is consistent with the theoretical value of 3.5鈥?.0 eV. The measured I鈥揤 curves show scaling with respect to the printed Au electrode area with lateral dimensions ranging from 80 nm to 7 渭m. These results demonstrate that PFPE-assisted nTP is a promising technique for producing potentially scalable and permanent MMM junctions. They also demonstrate that MMM structures (produced by the unique PFPE-assisted nTP) constitute a reliable test bed for exploring molecule-based electronics.