Measuring Relative Barrier Heights in Molecular Electronic Junctions with Transition Voltage Spectroscopy

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• 作者：Jeremy M. Beebe ; BongSoo Kim ; C. Daniel Frisbie ; James G. Kushmerick
• 刊名：ACS Nano
• 出版年：2008
• 出版时间：May 2008
• 年：2008
• 卷：2
• 期：5
• 页码：827-832
• 全文大小：302K
• 年卷期：0
• ISSN：1936-086X

文摘

Though molecular devices exhibiting potentially useful electrical behavior have been demonstrated, a deep understanding of the factors that influence charge transport in molecular electronic junctions has yet to be fully realized. Recent work has shown that a mechanistic transition occurs from direct tunneling to field emission in molecular electronic devices. The magnitude of the voltage required to enact this transition is molecule-specific, and thus measurement of the transition voltage constitutes a form of spectroscopy. Here we determine that the transition voltage for a series of alkanethiol molecules is invariant with molecular length, while the transition voltage of a conjugated molecule depends directly on the manner in which the conjugation pathway has been extended. Finally, by examining the transition voltage as a function of contact metal, we show that this technique can be used to determine the dominant charge carrier for a given molecular junction.