5 research outputs found
Simulation of dimensionality effects in thermal transport
The discovery of nanostructures and the development of growth and fabrication
techniques of one- and two-dimensional materials provide the possibility to
probe experimentally heat transport in low-dimensional systems. Nevertheless
measuring the thermal conductivity of these systems is extremely challenging
and subject to large uncertainties, thus hindering the chance for a direct
comparison between experiments and statistical physics models. Atomistic
simulations of realistic nanostructures provide the ideal bridge between
abstract models and experiments. After briefly introducing the state of the art
of heat transport measurement in nanostructures, and numerical techniques to
simulate realistic systems at atomistic level, we review the contribution of
lattice dynamics and molecular dynamics simulation to understanding nanoscale
thermal transport in systems with reduced dimensionality. We focus on the
effect of dimensionality in determining the phononic properties of carbon and
semiconducting nanostructures, specifically considering the cases of carbon
nanotubes, graphene and of silicon nanowires and ultra-thin membranes,
underlying analogies and differences with abstract lattice models.Comment: 30 pages, 21 figures. Review paper, to appear in the Springer Lecture
Notes in Physics volume "Thermal transport in low dimensions: from
statistical physics to nanoscale heat transfer" (S. Lepri ed.
Calculating thermal conductivity in a transient conduction regime: theory and implementation
SixGe1-x alloy as efficient phonon barrier in Ge/Si superlattices for thermoelectric applications
Thermal transport in free-standing silicon membranes: influence of dimensional reduction and surface nanostructures
Nanostructuring provides a viable route to improve the thermoelectric performance of materials, even of those that in bulk form have very low figure of merit. This strategy would potentially enable the fabrication of thermoelectric devices based on silicon, the cheapest, most integrable and easiest to dope Earth-abundant semiconductor. A drastic reduction of the thermal conductivity, which would lead to a proportional enhancement of the figure of merit, was observed for silicon low-dimensional nanostructures, such as nanowires and ultra-thin membranes. Here we provide a detailed analysis of the phononic properties of the latter, and we show that dimensionality reduction alone is not sufficient to hinder heat transport to a great extent. In turn, the presence of surface roughness at the nanoscale reduces the thermal conductivity of sub-10 nm membranes up to 10 times with respect to bulk
Simulation of Dimensionality Effects in Thermal Transport
The discovery of nanostructures and the development of growth and fabrication techniques of one- and two-dimensional materials provide the possibility to probe experimentally heat transport in low-dimensional systems. Nevertheless measuring the thermal conductivity of these systems is extremely challenging and subject to large uncertainties, thus hindering the chance for a direct comparison between experiments and statistical physics models. Atomistic simulations of realistic nanostructures provide the ideal bridge between abstract models and experiments. After briefly introducing the state of the art of heat transport measurement in nanostructures, and numerical techniques to simulate realistic systems at atomistic level, we review the contribution of lattice dynamics and molecular dynamics simulation to understanding nanoscale thermal transport in systems with reduced dimensionality. We focus on the effect of dimensionality in determining the phononic properties of carbon and semiconducting nanostructures, specifically considering the cases of carbon nanotubes, graphene and of silicon nanowires and ultra-thin membranes, underlying analogies and differences with abstract lattice models