Tuning the phonon transport in bilayer graphene to an anomalous regime dominated by electron-phonon scattering

2021 ◽  
Vol 104 (10) ◽  
Author(s):  
Xiaolong Yang ◽  
Zhe Liu ◽  
Fanchen Meng ◽  
Wu Li
Keyword(s):  
Phonon Scattering ◽  
Bilayer Graphene ◽  
Phonon Transport ◽  
Electron Phonon Scattering

scholarly journals Body-centered-cubic structure and weak anharmonic phonon scattering in tungsten

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Yani Chen ◽  
Jinlong Ma ◽  
Shihao Wen ◽  
Wu Li
Keyword(s):  
Phonon Scattering ◽  
Phonon Transport ◽  
High Symmetry ◽  
Body Centered Cubic ◽  
Phonon Branch ◽  
High Frequencies ◽  
Transverse Acoustic ◽  
Two Factors ◽  
Electron Phonon Scattering ◽  
Isotropy Condition

Abstract It was recently found that the anharmonic phonon–phonon scattering in tungsten is extremely weak at high frequencies, leading to a predominance of electron–phonon scattering and consequently anomalous phonon transport behaviors. In this work, we calculate the phonon linewidths of W along high-symmetry directions from first principles. We find that the weak phonon–phonon scattering can be traced back to two factors. The first is the triple degeneracy of the phonon branches at the P and H points, a universal property of elemental body-centered-cubic (bcc) structures. The second is a relatively isotropic character of the phonon dispersions. When both are met, phonon–phonon scattering rates must vanish at the P and H points. The weak phonon–phonon scattering feature is also applicable to Mo and Cr. However, in other elemental bcc substances like Na, the isotropy condition is violated due to the unusually soft character of the lower transverse acoustic phonon branch along the Γ-N direction, opening emission channels and leading to much stronger phonon–phonon scattering. We also look into the distributions of electron mean-free paths (MFPs) at room temperature in tungsten, which can help engineer the resistivity of nanostructured W for applications such as interconnects.

The effect of nickel doping on electron and phonon transport in the n-type nanostructured thermoelectric material CoSbS

2015 ◽  
Vol 3 (40) ◽  
pp. 10442-10450 ◽  
Author(s):  
Zihang Liu ◽  
Huiyuan Geng ◽  
Jing Shuai ◽  
Zhengyun Wang ◽  
Jun Mao ◽  
...  
Keyword(s):  
Effective Mass ◽  
Carrier Concentration ◽  
Thermoelectric Material ◽  
Phonon Scattering ◽  
Phonon Transport ◽  
Strong Electron ◽  
Nickel Doping ◽  
Electron Phonon Scattering

The optimized carrier concentration, high effective mass and strong electron–phonon scattering for Ni doped CoSbS contribute to the enhanced ZT value.

scholarly journals Electron-phonon scattering and in-plane electric conductivity in twisted bilayer graphene

2016 ◽  
Vol 94 (24) ◽  
Author(s):  
N. Ray ◽  
M. Fleischmann ◽  
D. Weckbecker ◽  
S. Sharma ◽  
O. Pankratov ◽  
...  
Keyword(s):  
Electric Conductivity ◽  
Phonon Scattering ◽  
Bilayer Graphene ◽  
Twisted Bilayer Graphene ◽  
Electron Phonon Scattering

Simulation of Sub-Micron Thermal Transport in a MOSFET Using a Hybrid Fourier-BTE Model

2010 ◽  
Author(s):  
James M. Loy ◽  
Dhruv Singh ◽  
Jayathi Y. Murthy
Keyword(s):  
Thermal Transport ◽  
Source Term ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Computational Cost ◽  
Phonon Transport ◽  
Boltzmann Transport ◽  
Hybrid Solver ◽  
Solution Methodology ◽  
Electron Phonon Scattering

Self-heating has emerged as a critical bottleneck to scaling in modern transistors. In simulating heat conduction in these devices, it is important to account for the granularity of phonon transport since electron-phonon scattering occurs preferentially to select phonon groups. However, a complete accounting for phonon dispersion, polarization and scattering is very expensive if the Boltzmann transport equation (BTE) is used. Moreover, difficulties with convergence are encountered when the phonon Knudsen number becomes small. In this paper we simulate a two-dimensional bulk MOSFET hotspot problem using a partially-implicit hybrid BTE-Fourier solver which is significantly less expensive than a full BTE solution, and which shows excellent convergence characteristics. Volumetric heat generation from electron-phonon collisions is taken from a Monte Carlo simulation of electron transport and serves as a heat source term in the governing transport equations. The hybrid solver is shown to perform well in this highly non-equilibrium situation, matching the solutions obtained from a pure all-BTE solution, but at significantly lower computational cost. The paper establishes that this new model and solution methodology are viable for the simulation of thermal transport in other emerging transistor designs and in other nanotechnology applications as well.

Non-Equilibrium Phonon Distributions in Sub-100nm Silicon Transistors

2005 ◽  
Vol 128 (7) ◽  
pp. 638-647 ◽  
Author(s):  
S. Sinha ◽  
E. Pop ◽  
R. W. Dutton ◽  
K. E. Goodson
Keyword(s):  
Phonon Scattering ◽  
Semiconductor Device ◽  
Transport Model ◽  
Ballistic Transport ◽  
Longitudinal Optical ◽  
Phonon Transport ◽  
Silicon Transistors ◽  
Zero Group ◽  
Electron Phonon Scattering ◽  
Non Equilibrium

Intense electron-phonon scattering near the peak electric field in a semiconductor device results in nanometer-scale phonon hotspots. Past studies have argued that ballistic phonon transport near such hotspots serves to restrict heat conduction. We reexamine this assertion by developing a new phonon transport model. In a departure from previous studies, we treat isotropic dispersion in all phonon branches and include a phonon emission spectrum from independent Monte Carlo simulations of electron-phonon scattering. We cast the model in terms of a non-equilibrium phonon distribution function and compare predictions from this model with data for ballistic transport in silicon. The solution to the steady-state transport equations for bulk silicon transistors shows that energy stagnation at the hotspot results in an excess equivalent temperature rise of about 13% in a 90nm gate-length device. Longitudinal optical phonons with non-zero group velocities dominate transport. We find that the resistance associated with ballistic transport does not overwhelm that from the package unless the peak power density approaches 50W∕μm3. A transient calculation shows negligible phonon accumulation and retardation between successive logic states. This work highlights and reduces the knowledge gaps in the electro-thermal simulation of transistors.

TEMPERATURE DEPENDENCE BEHAVIOR OF ELECTRICAL RESISTIVITY IN NOBLE METALS AT LOW TEMPERATURES

2014 ◽  
Vol 5 (3) ◽  
pp. 982-992 ◽  
Author(s):  
M AL-Jalali
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Temperature Dependence ◽  
Concentration Dependence ◽  
Low Temperatures ◽  
Noble Metals ◽  
Phonon Scattering ◽  
Theoretical Models ◽  
Residual Resistivity ◽  
Electron Phonon Scattering

Resistivity temperature – dependence and residual resistivity concentration-dependence in pure noble metals(Cu, Ag, Au) have been studied at low temperatures. Dominations of electron – dislocation and impurity, electron-electron, and electron-phonon scattering were analyzed, contribution of these mechanisms to resistivity were discussed, taking into consideration existing theoretical models and available experimental data, where some new results and ideas were investigated.

scholarly journals When band convergence is not beneficial for thermoelectrics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Junsoo Park ◽  
Maxwell Dylla ◽  
Yi Xia ◽  
Max Wood ◽  
G. Jeffrey Snyder ◽  
...  
Keyword(s):  
Charge Carrier ◽  
First Principles ◽  
Design Principle ◽  
Phonon Scattering ◽  
Charge Carrier Concentration ◽  
Deformation Potential ◽  
Interband Scattering ◽  
Improved Performance ◽  
Full Heusler ◽  
Electron Phonon Scattering

AbstractBand convergence is considered a clear benefit to thermoelectric performance because it increases the charge carrier concentration for a given Fermi level, which typically enhances charge conductivity while preserving the Seebeck coefficient. However, this advantage hinges on the assumption that interband scattering of carriers is weak or insignificant. With first-principles treatment of electron-phonon scattering in the CaMg2Sb2-CaZn2Sb2 Zintl system and full Heusler Sr2SbAu, we demonstrate that the benefit of band convergence can be intrinsically negated by interband scattering depending on the manner in which bands converge. In the Zintl alloy, band convergence does not improve weighted mobility or the density-of-states effective mass. We trace the underlying reason to the fact that the bands converge at a one k-point, which induces strong interband scattering of both the deformation-potential and the polar-optical kinds. The case contrasts with band convergence at distant k-points (as in the full Heusler), which better preserves the single-band scattering behavior thereby successfully leading to improved performance. Therefore, we suggest that band convergence as thermoelectric design principle is best suited to cases in which it occurs at distant k-points.

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