TY - JOUR
T1 - Simultaneous nanoindentation and electron tunneling through alkanethiol self-assembled monolayers
AU - Engelkes, Vincent B.
AU - Daniel Frisbie, C.
PY - 2006/5/25
Y1 - 2006/5/25
N2 - Electrical tunnel junctions consisting of alkanethiol molecules self-assembled on Au-coated Si substrates and contacted with Au-coated atomic force microscopy tips were characterized under varying junction loads in a conducting-probe atomic force microscopy configuration. Junction load was cycled in the fashion of a standard nanoindentation experiment; however, junction conductance rather than probe depth was measured directly. The junction conductance data have been analyzed with typical contact mechanics (Derjaguin-Müller-Toporov) and tunneling equations to extract the monolayer modulus (∼50 GPa), the contact transmission (-2 × 10-6), contact area, and probe depth as a function of load. The monolayers are shown to undergo significant plastic deformation under compression, yielding indentations ∼7 Å deep for maximum junction loads of ∼50 nN. Comparison of mechanical properties for different chain lengths was also performed. The film modulus decreased with the number of carbons in the molecular chain for shorter-chain films. This trend, abruptly reversed once 12 carbons were present along the backbone.
AB - Electrical tunnel junctions consisting of alkanethiol molecules self-assembled on Au-coated Si substrates and contacted with Au-coated atomic force microscopy tips were characterized under varying junction loads in a conducting-probe atomic force microscopy configuration. Junction load was cycled in the fashion of a standard nanoindentation experiment; however, junction conductance rather than probe depth was measured directly. The junction conductance data have been analyzed with typical contact mechanics (Derjaguin-Müller-Toporov) and tunneling equations to extract the monolayer modulus (∼50 GPa), the contact transmission (-2 × 10-6), contact area, and probe depth as a function of load. The monolayers are shown to undergo significant plastic deformation under compression, yielding indentations ∼7 Å deep for maximum junction loads of ∼50 nN. Comparison of mechanical properties for different chain lengths was also performed. The film modulus decreased with the number of carbons in the molecular chain for shorter-chain films. This trend, abruptly reversed once 12 carbons were present along the backbone.
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U2 - 10.1021/jp055567m
DO - 10.1021/jp055567m
M3 - Article
C2 - 16706460
AN - SCOPUS:33745781532
SN - 1520-6106
VL - 110
SP - 10011
EP - 10020
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 20
ER -