105 research outputs found
InGaAs/GaAs/alkanethiolate radial superlattices: Experimental
A radial InGaAs/GaAs/1-hexadecanethiol superlattice is fabricated by the
roll-up of a strained InGaAs/GaAs bilayer passivated with a molecular
self-assembled monolayer. Our technique allows the formation of multi-period
inorganic/organic hybrid heterostructures. This paper contains the detailed
experimental description of how to fabricate these structures.Comment: 2 pages, no figures, Version 2; minor changes (fixed typos and update
references
Flexible and Transparent All-Graphene Circuits for Quaternary Digital Modulations
In modern communication system, modulation is a key function that embeds the
baseband signal (information) into a carrier wave so that it can be
successfully broadcasted through a medium such as air or cables. A flexible
signal modulation scheme is hence essential to wide range of applications based
on flexible electronics. Here we report a fully bendable all-graphene modulator
circuit with the capability to encode a carrier signal with quaternary digital
information for the first time. By exploiting the ambipolarity and the
nonlinearity in a graphene transistor, we demonstrated two types of quaternary
modulation schemes: 4-ary amplitude-shift keying (4-ASK) and quadrature
phase-shift keying (QPSK). Remarkably, 4-ASK and QPSK can be realized with just
1 and 2 all-graphene transistors, respectively, representing a drastic
reduction in circuit complexity when compared with conventional digital
modulators. In addition, the circuit is not only flexible but also highly
transparent (~95% transmittance) owing to their all-graphene design with every
component (channel, interconnects, load resistor, and source/drain/gate
electrodes) fabricated from graphene films. Taken together, these results
represent a significant step toward achieving a high speed communication system
that can be monolithically integrated on a flexible and transparent platform.Comment: 29 pages, 8 figures, 1 tabl
Stencil Nano Lithography Based on a Nanoscale Polymer Shadow Mask: Towards Organic Nanoelectronics
A stencil lithography technique has been developed to fabricate organic-material-based electronic devices with sub-micron resolution. Suspended polymethylmethacrylate ( PMMA) membranes were used as shadow masks for defining organic channels and top electrodes. Arrays of pentacene field effect transistors (FETs) with various channel lengths from 50 mu m down to 500 nm were successfully produced from the same batch using this technique. Electrical transport measurements showed that the electrical contacts of all devices were stable and the normalized contact resistances were much lower than previously studied organic FETs. Scaling effects, originating from the bulk space charge current, were investigated by analyzing the channel-length-dependent mobility and hysteresis behaviors. This novel lithography method provides a reliable means for studying the fundamental transport properties of organic materials at the nanoscale as well as enabling potential applications requiring the fabrication of integrated organic nanoelectronic devices.open1155sciescopu
Mechanical force sensors using organic thin-film transistors
The pressure dependence of pentacene (C22H14) transistors with solution-processed polyvinylphenol gate dielectric on glass substrates is investigated by applying uniaxial mechanical pressure with a needle. We found that organic thin-film transistors are sensitive to applied pressure inherently. The measurements reveal a reversible current dependence of the transfer characteristics where the drain current is switching between two states. Experimental and simulation results suggest that switch-on voltage and interface resistance are affected. The change takes seconds, hinting at trap states being responsible for the effect. (C) 2005 American Institute of Physics
Contact properties of high-mobility, air-stable, low-voltage organic n-channel thin-film transistors based on a naphthalene tetracarboxylic diimide
Air-stable bottom-gate, top-contact n-channel organic transistors based on a naphthalene diimide exhibiting electron mobilities up to 0.8 cm(2)/Vs at low voltages were fabricated. Transistors with channel lengths of 1 mu m show a transconductance of 60 mS/m, but are significantly limited by the contact resistance. Transmission line measurements in combination with contact resistance models were applied to investigate this influence. Both contact resistance and contact resistivity are proportional to the inverse gate overdrive voltage. Organic complementary ring oscillators were fabricated on a flexible plastic substrate showing record signal delays down to 17 mu s at a supply voltage of 2.6 V. (C) 2013 AIP Publishing LLC
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