70 research outputs found
Interface Dipole : Effects on Threshold Voltage and Mobility for both Amorphous and Poly-crystalline Organic Field Effect Transistors
We report a detailed comparison on the role of a self-assembled monolayer
(SAM) of dipolar molecules on the threshold voltage and charge carrier mobility
of organic field-effect transistor (OFET) made of both amorphous and
polycrystalline organic semiconductors. We show that the same relationship
between the threshold voltage and the dipole-induced charges in the SAM holds
when both types of devices are fabricated on strictly identical base
substrates. Charge carrier mobilities, almost constant for amorphous OFET, are
not affected by the dipole in the SAMs, while for polycrystalline OFET
(pentacene) the large variation of charge carrier mobilities is related to
change in the organic film structure (mostly grain size).Comment: Full paper and supporting informatio
Physical Study by Surface Characterizations of Sarin Sensor on the Basis of Chemically Functionalized Silicon Nanoribbon Field Effect Transistor
Surface characterizations of an organophosphorus (OP) gas detector based on
chemically functionalized silicon nanoribbon field-effect transistor (SiNR-FET)
were performed by Kelvin Probe Force Microscopy (KPFM) and ToF-SIMS, and
correlated with changes in the current-voltage characteristics of the devices.
KPFM measurements on FETs allow (i) to investigate the contact potential
difference (CPD) distribution of the polarized device as function of the gate
voltage and the exposure to OP traces and, (ii) to analyze the CPD hysteresis
associated to the presence of mobile ions on the surface. The CPD measured by
KPFM on the silicon nanoribbon was corrected due to side capacitance effects in
order to determine the real quantitative surface potential. Comparison with
macroscopic Kelvin probe (KP) experiments on larger surfaces was carried out.
These two approaches were quantitatively consistent. An important increase of
the CPD values (between + 399 mV and + 302 mV) was observed after the OP sensor
grafting, corresponding to a decrease of the work function, and a weaker
variation after exposure to OP (between - 14 mV and - 61 mV) was measured.
Molecular imaging by ToF-SIMS revealed OP presence after SiNR-FET exposure. The
OP molecules were essentially localized on the Si-NR confirming effectiveness
and selectivity of the OP sensor. A prototype was exposed to Sarin vapors and
succeeded in the detection of low vapor concentrations (40 ppm).Comment: Paper and supporting information, J. Phys. Chem. C, 201
On the mechanical and electronic properties of thiolated gold nanocrystals
This article is part of themed collection: 2015 Hot Papers in Nanoscale.-- arXiv:1412.7698v1.-- et al.We present a quantitative exploration, combining experiment and simulation, of the mechanical and electronic properties, as well as the modifications induced by an alkylthiolated coating, at the single nanoparticle (NP) level. We determined the response of the NPs to external pressure in a controlled manner using an atomic force microscope tip. We found a strong reduction in their Young's modulus, as compared to bulk gold, and a significant influence of strain on the electronic properties of the alkylthiolated NPs. Electron transport measurements of tiny molecular junctions (NP/alkylthiol/CAFM tip) show that the effective tunnelling barrier through the adsorbed monolayer strongly decreases by increasing the applied load, which translates in a remarkable and unprecedented increase in the tunnel current. These observations are successfully explained using simulations based on the finite element analysis (FEA) and first-principles calculations that permit one to consider the coupling between the mechanical response of the system and the electric dipole variations at the interface.P.L. is a Senior Research Associate from the Fund for Scientific Research of Belgium (F.R.S. – FNRS). K.S. has been supported by the NordPas-de Calais Council fund and the ANR project SAGE III-V (no. ANR11BS1001203) and S.D. by EU project I-ONE (FP7 no. 280772). The experiments were partly funded by the SINGLEMOL project supported by the Nord-Pas-de Calais council fund. We also acknowledge funding from the Basque Government (Grant No. IT-756-13) and the Spanish MINECO (Grant Nos. MAT2013-46593-C6-2-P and FIS2013-48286-C2-2-P).Peer Reviewe
Oligothiophene-derivatized azobenzene as immobilized photoswitchable conjugated systems
Immobilization of an azobenzene-bithiophene compound on a gold surface leads to self-assembled monolayers with photoswitchable electrical properties
High on-off conductance switching ratio in light-driven self-assembled molecular devices
Date du colloque : 5-9/01/2010International audienc
OPTOSAM: Surfaces aux propriétés électroniques réversiblement modifiables par stimulation optique
Date du colloque : 10/2008</p
Surface Functionalization by Monolayers of Immobilized Thiophene-based Linear pi-Conjugated Systems
Date du colloque : 10/2008</p
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