Revisiting phonon transport in perovskite SrTiO3 : Anharmonic phonon renormalization and four-phonon scattering

2021 ◽  
Vol 104 (23) ◽  
Author(s):  
Qi Wang ◽  
Zezhu Zeng ◽  
Yue Chen
Keyword(s):  
Phonon Scattering ◽  
Phonon Transport ◽  
Phonon Renormalization

Study on Phonon Drag Effect and Phonon Transport in Thin Si-on-Insulator Layers

2015 ◽  
Vol 1117 ◽  
pp. 86-89 ◽  
Author(s):  
Hiroya Ikeda ◽  
Takuro Oda ◽  
Yuhei Suzuki ◽  
Yoshinari Kamakura ◽  
Faiz Salleh
Keyword(s):  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Phonon Scattering ◽  
Phonon Transport ◽  
Infrared Photodetector ◽  
Phonon Drag ◽  
Drag Effect ◽  
Phonon Modes ◽  
Highly Sensitive ◽  
Insulator Layers

The Seebeck coefficient of P-doped ultrathin Si-on-insulator (SOI) layers is investigated for the application to a highly-sensitive thermopile infrared photodetector. It is found that the Seebeck coefficient originating from the phonon drag is significant in the lightly doped region and depends on the carrier concentration with increasing carrier concentration above ~5×1018 cm-3. On the basis of Seebeck coefficient calculations considering both electron and phonon distribution, the phonon-drag part of SOI Seebeck coefficient is mainly governed by the phonon transport, in which the phonon-phonon scattering process is dominant rather than the crystal boundary scattering even in the SOI layer with a thickness of 10 nm. This fact suggests that the phonon-drag Seebeck coefficient is influenced by the phonon modes different from the thermal conductivity.

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.

Phonon Conduction Normal to Polysilicon Films on Diamond

2013 ◽  
Author(s):  
Jungwan Cho ◽  
Pane C. Chao ◽  
Mehdi Asheghi ◽  
Kenneth E. Goodson
Keyword(s):  
Thermal Conductivity ◽  
Transport Theory ◽  
Phonon Scattering ◽  
Phonon Transport ◽  
Silicon Films ◽  
Silicon Thin Films ◽  
Transmission Electron ◽  
Crystal Films ◽  
Polysilicon Films ◽  
Polycrystalline Silicon Films

Silicon films of thickness near and below one micrometer play a central role in many advanced technologies for computation and energy conversion. Numerous data on the thermal conductivity of silicon thin films are available in the literature, but mainly for the in-plane thermal conductivity of polycrystalline and single-crystal films. Here we use picosecond time-domain thermoreflectance (TDTR), transmission electron microscopy, and phonon transport theory to investigate heat conduction normal to polycrystalline silicon films on diamond substrates. The data agree with predictions that account for the coupled effects of phonon scattering on film boundaries and defects concentrated near grain boundaries. Using the data and the model, we estimate the polysilicon-diamond interface resistance to be 6.5–8 m2 K GW−1.

scholarly journals Direct observation of large electron–phonon interaction effect on phonon heat transport

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiawei Zhou ◽  
Hyun D. Shin ◽  
Ke Chen ◽  
Bai Song ◽  
Ryan A. Duncan ◽  
...  
Keyword(s):  
Heat Transport ◽  
Phonon Scattering ◽  
Crystalline Silicon ◽  
Substantial Reduction ◽  
Phonon Transport ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Exciting Electron ◽  
Energy Conversion Devices ◽  
The Impact

AbstractAs a foundational concept in many-body physics, electron–phonon interaction is essential to understanding and manipulating charge and energy flow in various electronic, photonic, and energy conversion devices. While much progress has been made in uncovering how phonons affect electron dynamics, it remains a challenge to directly observe the impact of electrons on phonon transport, especially at environmental temperatures. Here, we probe the effect of charge carriers on phonon heat transport at room temperature, using a modified transient thermal grating technique. By optically exciting electron-hole pairs in a crystalline silicon membrane, we single out the effect of the phonon–carrier interaction. The enhanced phonon scattering by photoexcited free carriers results in a substantial reduction in thermal conductivity on a nanosecond timescale. Our study provides direct experimental evidence of the elusive role of electron–phonon interaction in phonon heat transport, which is important for understanding heat conduction in doped semiconductors. We also highlight the possibility of using light to dynamically control thermal transport via electron–phonon coupling.

scholarly journals Thermal transport in nanocrystalline Si and SiGe by ab initio based Monte Carlo simulation

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Lina Yang ◽  
Austin J. Minnich
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Ab Initio ◽  
Grain Boundaries ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Computational Study ◽  
Phonon Transport ◽  
Nanocrystalline Si

Abstract Nanocrystalline thermoelectric materials based on Si have long been of interest because Si is earth-abundant, inexpensive, and non-toxic. However, a poor understanding of phonon grain boundary scattering and its effect on thermal conductivity has impeded efforts to improve the thermoelectric figure of merit. Here, we report an ab-initio based computational study of thermal transport in nanocrystalline Si-based materials using a variance-reduced Monte Carlo method with the full phonon dispersion and intrinsic lifetimes from first-principles as input. By fitting the transmission profile of grain boundaries, we obtain excellent agreement with experimental thermal conductivity of nanocrystalline Si [Wang et al. Nano Letters 11, 2206 (2011)]. Based on these calculations, we examine phonon transport in nanocrystalline SiGe alloys with ab-initio electron-phonon scattering rates. Our calculations show that low energy phonons still transport substantial amounts of heat in these materials, despite scattering by electron-phonon interactions, due to the high transmission of phonons at grain boundaries, and thus improvements in ZT are still possible by disrupting these modes. This work demonstrates the important insights into phonon transport that can be obtained using ab-initio based Monte Carlo simulations in complex nanostructured materials.

scholarly journals Anharmonic lattice dynamics and thermal transport in type-I inorganic clathrates

2022 ◽  
Author(s):  
Shravan Godse ◽  
Yagyank Srivastava ◽  
Ankit Jain
Keyword(s):  
Thermal Transport ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Host Lattice ◽  
Type I ◽  
Transport Channel ◽  
Anharmonic Lattice ◽  
Weak Binding ◽  
Phonon Renormalization ◽  
Inorganic Clathrates

Abstract The anharmonic phonon properties of type-I filled inorganic clathrates Ba8Ga16Ge30 and Sr8Ga16Ge30 are obtained from the first-principles calculations by considering the temperature-dependent sampling of the potential energy surface and quartic phonon renormalization. Owing to the weak binding of guest atoms with the host lattice, the obtained guest modes undergo strong renormalization with temperature and become stiffer by up to 50% at room temperature in Sr8Ga16Ge30. The calculated phonon frequencies and associated thermal mean squared displace- ments are comparable with experiments despite the on-centering of guest atoms at cage centers in both clathrates. Lattice thermal conductivities are obtained in the temperature range of 50- 300 K accounting for three-phonon scattering processes and multi-channel thermal transport. The contribution of coherent transport channel is significant at room temperature (13% and 22% in Ba8Ga16Ge30 and Sr8Ga16Ge30) but is insufficient to explain the experimentally observed glass-like thermal transport in Sr8Ga16Ge30.

Spectral Detail of Phonon Conduction and Scattering in Graphene

2011 ◽  
Author(s):  
Dhruv Singh ◽  
Jayathi Y. Murthy ◽  
Timothy S. Fisher
Keyword(s):  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Interatomic Potential ◽  
Phonon Dispersion ◽  
Transition Probabilities ◽  
Transition Probability ◽  
Phonon Transport ◽  
Temperature Perturbation ◽  
Boltzmann Transport ◽  
Wide Range

This paper examines the thermodynamic and thermal transport properties of the 2D graphene lattice. The interatomic interactions are modeled using the Tersoff interatomic potential and are used to evaluate phonon dispersion curves, density of states and thermodynamic properties of graphene as functions of temperature. Perturbation theory is applied to calculate the transition probabilities for three-phonon scattering. The matrix elements of the perturbing Hamiltonian are calculated using the anharmonic interatomic force constants obtained from the interatomic potential as well. An algorithm to accurately quantify the contours of energy balance for three-phonon scattering events is presented and applied to calculate the net transition probability from a given phonon mode. Under the linear approximation, the Boltzmann transport equation (BTE) is applied to compute the thermal conductivity of graphene, giving spectral and polarization-resolved information. Predictions of thermal conductivity for a wide range of parameters elucidate the behavior of diffusive phonon transport. The complete spectral detail of selection rules, important phonon scattering pathways, and phonon relaxation times in graphene are provided, contrasting graphene with other materials, along with implications for graphene electronics. We also highlight the specific scattering processes that are important in Raman spectroscopy based measurements of graphene thermal conductivity, and provide a plausible explanation for the observed dependence on laser spot size.

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