University PhD Dissertation Defense Michael J. Preiner
Michael John Preiner
mpreiner at stanford.edu
Tue Jun 2 09:42:04 PDT 2009
Department of Applied Physics
University PhD Dissertation Defense
Electronic and Optical Spectroscopy of Molecular Junctions
Michael John Preiner
Research Advisor: Nicholas Melosh
3 June 2009 @1:30 p.m.
(Refreshments served at 1:15 p.m.)
Allen Building (Formerly CIS-X), Room 101
Electronic transport through molecules has been intensively studied in recent years, due to scientific interest in fundamental questions about charge transport and the technological promise of nanoscale circuitry. A wide range of range of experimental platforms have been developed to electronically probe both single molecules and molecular monolayers. However, it remains challenging to fabricate reliable electronic contacts to molecules, and the vast majority of molecular electronic architectures are not amenable to standard characterization techniques, such as optical spectroscopy. Thus the field of molecular electronics has been hampered with problems of reproducibility, and many fundamental questions about transport and switching behavior remain unanswered.
In the work I will present, we have developed a new method for creating robust, large area junctions where the electronic transport is through a single monolayer of molecules. This method utilizes atomic layer deposition (ALD) to grow an ultrathin oxide layer on top of a molecular monolayer, which passivates defects and protects the molecules against subsequent processing. I will also show how this method can be be adapted to provide a mechanism for rapid imaging and analysis of single defects in molecular monolayers. I will then present results of spectroscopy of these molecular electronic junctions using optically excited hot electrons. Finally, I will discuss methods of coupling surface plasmons to these molecular junctions to greatly increase the light intensity within the molecular layer, which presents a major step towards in-situ optical spectroscopy of active molecular junctions.
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