Analysis of phonon transport in silicon nanowires including optical phonons

2013 ◽  
Vol 63 (5) ◽  
pp. 1007-1013 ◽  
Author(s):  
Jae Sik Jin ◽  
Bong Jae Lee ◽  
Hyun Jin Lee
Keyword(s):  
Silicon Nanowires ◽  
Phonon Transport ◽  
Optical Phonons

Electron-Phonon Interaction and Joule Heating in Nanostructures

2008 ◽  
Author(s):  
Eric Pop
Keyword(s):  
Carbon Nanotubes ◽  
Electric Fields ◽  
Joule Heating ◽  
Optical Phonon ◽  
Phonon Transport ◽  
Phonon Energy ◽  
Strained Silicon ◽  
Vibrational Modes ◽  
Optical Phonons ◽  
Ambient Gas

The electron-phonon energy dissipation bottleneck is examined in silicon and carbon nanoscale devices. Monte Carlo simulations of Joule heating are used to investigate the spectrum of phonon emission in bulk and strained silicon. The generated phonon distributions are highly non-uniform in energy and momentum, although they can be approximately grouped into one third acoustic (AC) and two thirds optical phonons (OP) at high electric fields. The phonon dissipation is markedly different in strained silicon at low electric fields, where certain relaxation mechanisms are blocked by scattering selection rules. In very short (∼10 nm) silicon devices, electron and phonon transport is quasi-ballistic, and the heat generation domain is much displaced from the active device region, into the contact electrodes. The electron-phonon bottleneck is more severe in carbon nanotubes, where the optical phonon energy is three times higher than in silicon, and the electron-OP interaction is entirely dominant at high fields. Thus, persistent hot optical phonons are easily generated under Joule heating in single-walled carbon nanotubes suspended between two electrodes, in vacuum. This leads to negative differential conductance at high bias, light emission, and eventual breakdown. Conversely, optical and electrical measurements on such nanotubes can be used to gauge their thermal properties. The hot optical phonon effects appear less pronounced in suspended nanotubes immersed in an ambient gas, suggesting that phonons find relaxation pathways with the vibrational modes of the ambient gas molecules. Finally, hot optical phonons are least pronounced for carbon nanotube devices lying on dielectrics, where the OP modes can couple into the vibrational modes of the substrate. Such measurements and modeling suggest very interesting, non-equilibrium coupling between electrons and phonons in solid-state devices at nanometer length and picoseconds time scales.

Length Scale of Diffusive Phonon Transport in Suspended Thin Silicon Nanowires

Nano Letters ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 276-283 ◽  
Author(s):  
Shyamprasad N. Raja ◽  
Reto Rhyner ◽  
Kantawong Vuttivorakulchai ◽  
Mathieu Luisier ◽  
Dimos Poulikakos
Keyword(s):  
Silicon Nanowires ◽  
Phonon Transport ◽  
Length Scale ◽  
Thin Silicon

scholarly journals Electron transport in silicon nanowires having different cross-sections

2016 ◽  
Vol 7 (2) ◽  
pp. 8-25 ◽  
Author(s):  
Orazio Muscato ◽  
Tina Castiglione
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Silicon Nanowires ◽  
Maximum Entropy Principle ◽  
Optical Phonons ◽  
Poisson System ◽  
Moment System ◽  
Entropy Principle ◽  
Closure Relations ◽  
The Moment

AbstractTransport phenomena in silicon nanowires with different cross-section are investigated using an Extended Hydrodynamic model, coupled to the Schrödinger-Poisson system. The model has been formulated by closing the moment system derived from the Boltzmann equation on the basis of the maximum entropy principle of Extended Thermodynamics, obtaining explicit closure relations for the high-order fluxes and the production terms. Scattering of electrons with acoustic and non polar optical phonons have been taken into account. The bulk mobility is evaluated for square and equilateral triangle cross-sections of the wire.

Enormous suppression of phonon transport in silicon nanowires with five-fold twin boundary

2018 ◽  
Vol 6 (38) ◽  
pp. 18533-18542 ◽  
Author(s):  
Yufei Gao ◽  
Yanguang Zhou ◽  
Ming Hu
Keyword(s):  
Twin Boundary ◽  
Silicon Nanowires ◽  
Phonon Transport ◽  
Boundary Scattering

The five-fold twin boundary not only leads to much more intense boundary scattering, but also results in vibrational hybridization.

Micro- and Nanoscale Phonon Heat Transport in Silicon

Volume 4 ◽  
2004 ◽  
Author(s):  
Y. Ju
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nanowires ◽  
Phonon Dispersion ◽  
Transport Model ◽  
Phonon Transport ◽  
Conductivity Data ◽  
Phonon Modes ◽  
Conductivity Model ◽  
Thermal Conductivity Data ◽  
Thermal Conductivity Model

Micro- and nanoscale energy transport in semiconductors is one of the critical research areas for emerging nano-electronics. Key features of phonon dispersion curves are re-examined, which motivates the use of phonon density of states obtained from ab initio calculations as a basis for constructing a semi-phenomenological thermal conductivity model. Thermal conductivity data on silicon nanowires are analyzed to identify dominant phonon modes. The consistency of the present thermal conductivity model is examined by comparing its prediction with the thermal conductivity data from bulk germanium samples with controlled amount of point defects. The thermal conductivity modeling study provides input parameters for a two-fluid phonon transport model for silicon and related semiconductors, which can play an important role in computer aided design of nanoelectronic devices and simulation of ultra-fast phenomena.

Surface morphology and strain coupling effects on phonon transport in silicon nanowires

2016 ◽  
Vol 3 (8) ◽  
pp. 2759-2765 ◽  
Author(s):  
Xiangjun Liu ◽  
Gang Zhang ◽  
Qing-Xiang Pei ◽  
Yong-Wei Zhang
Keyword(s):  
Surface Morphology ◽  
Silicon Nanowires ◽  
Phonon Transport ◽  
Coupling Effects ◽  
Strain Coupling

Curvature Effect on the Thermal Conductivity of Nanowires

2008 ◽  
Author(s):  
Liang-Chun Liu ◽  
Mei-Jiau Huang ◽  
Ronggui Yang
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Effective Thermal Conductivity ◽  
Silicon Nanowires ◽  
Phonon Transport ◽  
Curvature Effect ◽  
Transport Efficiency ◽  
Directional Preference ◽  
Monte Carlo Simulator ◽  
Thermal Conductivities

Directional preference of the ballistic phonon transport plays an important role in the effective thermal conductivity of nanostructures. Curved nanowires can have very different thermal conductivities from straight ones. In this work, a Monte-Carlo simulator is developed and used to investigate the curvature effect on the phonon transport in silicon nanowires. The results show that the curvature of geometry does not alter the phonon transport efficiency in large wires but decreases the effective thermal conductivity in their nano-sized counterparts.

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