333 research outputs found
Thermal transport in MoS2 from molecular dynamics using different empirical potentials
Get PDFThermal properties of molybdenum disulfide (MoS2) have recently attracted attention related to fundamentals
of heat propagation in strongly anisotropic materials, and in the context of potential applications to optoelectronics and thermoelectrics. Multiple empirical potentials have been developed for classical molecular dynamics
(MD) simulations of this material, but it has been unclear which provides the most realistic results. Here, we
calculate lattice thermal conductivity of single- and multilayer pristine MoS2 by employing three different
thermal transport MD methods: equilibrium, nonequilibrium, and homogeneous nonequilibrium ones. We mainly
use the Graphics Processing Units Molecular Dynamics code for numerical calculations, and the Large-scale
Atomic/Molecular Massively Parallel Simulator code for crosschecks. Using different methods and computer
codes allows us to verify the consistency of our results and facilitate comparisons with previous studies, where
different schemes have been adopted. Our results using variants of the Stillinger-Weber potential are at odds
with some previous ones and we analyze the possible origins of the discrepancies in detail. We show that, among
the potentials considered here, the reactive empirical bond order (REBO) potential gives the most reasonable
predictions of thermal transport properties as compared to experimental data. With the REBO potential, we
further find that isotope scattering has only a small effect on thermal conduction in MoS2 and the in-plane thermal
conductivity decreases with increasing layer number and saturates beyond about three layers. We identify the
REBO potential as a transferable empirical potential for MD simulations of MoS2 which can be used to study
thermal transport properties in more complicated situations such as in systems containing defects or engineered
nanoscale features. This work establishes a firm foundation for understanding heat transport properties of MoS2
using MD simulations
Graphene-based Nanostructures and DNA-based Biomolecule Sensors
No full textFor the past forty years, the entire electronics industry has been pushing the boundaries of innovation in order to make devices with higher speed, smaller size and increased complexity while at the same time maintaining low power consumption and low cost. After the first appearance of CNT in 1990 carbon has emerged as a front-runner underlying carbon-based nanotechnology. Carbon has various crystalline allotropes such as diamond, graphite, graphene, nanotubes and Buckminsterfullerenes. Since the discovery of the technique to produce graphene flakes called mechanical exfoliation in 2004, graphene has been claimed as the saviour of Moore's law. Graphene research has been mostly focused on transistors and thin film applications, but the interest in different applications of graphene is growing rapidly. Of all of the suggested applications of graphene, the use of graphene to make graphene-based field effect transistor seems the one most closest to emerge.
This research work contains three main parts. The first part is to investigate the electrical conductivity and dielectric properties of PMMA/Graphene Nanoplatelet composites with an emphasis on the percolation threshold. The second part is the study of a graphene-based FET structure including modelling the FET characteristics based on device theory calculation and simulation, and utilizing Raman Spectroscopy and Surface-Enhanced Raman Spectroscopy to verify active molecular components inside synthesized nanostructures. The third part is the sensor experiment part, which includes design, fabrication and testing of two biomolecular sensors using optical photolumescence measurements and graphene-based electrochemical measurements, respectively
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