Electrical and Spectroscopic Characterization of Metal-Molecule-Metal Junctions
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Date: 03-22-2006
Start Time:
4:00pm
End Time: 5:00pm
Speaker: Theresa Mayer
From:
Penn State University
Location: Interschool Lab, 7th floor, Schapiro/CEPSR
Hosted by:
Center for Integrated Science
Abstract:
Considerable attention has been devoted to developing an understanding
of the mechanisms that dominate electrical transport in
metal-molecule-metal junctions comprised of single and small ensembles
of molecules. In this talk, we will present an overview of recent
research on the electrical and spectroscopic characterization of
molecular junctions inserted along the length of sub-40-nm diameter Au
and Pd metal nanowires (i.e., in-wire junctions) fabricated by
template-directed synthesis. In particular, we will show results that
investigate the relationship between the temperature dependent (10 ¡V
300 K) current-voltage (I-V) characteristics and the vibrational
spectra measured by inelastic electron tunneling (IET) spectroscopy for
candidate molecular wires and bistable switching molecules. The two
types of molecular wire junctions that were studied incorporate a self
assembled monolayer of dithiolated oligo (phenylene-ethynylene) (OPE)
molecules and their -NO2 derivatives. The I-V of these junctions are
stable and reproducible between +/-1V. Temperature independent I-V are
measured for both types of junctions, which is indicative of coherent
tunneling transport. Moreover, strong vibrations associated with
Č(18b) and Č(19a) ring modes were observed in both junctions. In
contrast, measurements of molecular junctions that incorporate SAMs
based on aniline derivatives show reproducible bistable switching with
an on-off ratio of >10:1 at 1V. Differences are observed in the
vibrational spectra that depend on the state of the junction.
Theresa S. Mayer received the B.S. degree in Electrical Engineering
from Virginia Tech in 1988, and the M.S. and Ph.D. degrees in
Electrical Engineering from Purdue University in 1989 and 1993. In
1994, she joined the Department of Electrical Engineering at Penn State
University-University Park, where she is a Professor. Her research
interests are in semiconductor and molecular device fabrication,
integration, and characterization. Her research activities have
included investigating high-speed III-V electronic devices,
metallodielectric frequency selective surfaces, heterogeneous
integration of micro- and nanometer-scale devices, molecular electronic
devices, and nanosensor transducer arrays. Prof. Mayer was a Kodak
Fellow (1990-1993) and the recipient of a National Science Foundation
CAREER Award (1995), and a Penn State Engineering Society Outstanding
Teaching Award (2000). She currently serves the general chair of the
IEEE Device Research Conference and the chair of the Gordon Research
Conference on the Chemistry and Physics of Nanostructure Fabrication.