Phonon wave-packet dynamics at semiconductor interfaces by molecular-dynamics simulation

Schelling, Patrick K.; Phillpot, Simon R.; Keblinski, Pawel

doi:10.1063/1.1465106

Cited by 314 publications

(257 citation statements)

References 10 publications

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“…To understand the difference of interfacial thermal conductance at ZZ and ZZ57 interfaces, the phonon transmission process across the interfaces was investigated using the phonon wave packet method 45,46 . Phonon wave packets are formed from a linear combination of vibration eigenstates of the crystalline lattices.…”

Section: In-plane Interfacial Binding Between Mos 2 and Graphenementioning

confidence: 99%

MoS2-graphene in-plane contact for high interfacial thermal conduction

et al. 2017

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Recent studies showed that the in-plane and inter-plane thermal conductivities of twodimensional (2D) MoS 2 are low, posing a significant challenge in heat management in MoS 2 -based electronic devices. To address this challenge, we design the interfaces between MoS 2 and graphene by fully utilizing graphene, a 2D material with an ultra-high thermal conduction. We first perform ab initio atomistic simulations to understand the bonding nature and structure stability of the interfaces. Our results show that the designed interfaces, which are found to be connected together by strong covalent bonds between Mo and C atoms, are energetically stable.We then perform molecular dynamics simulations to investigate the interfacial thermal conductance. It is found surprisingly that the interface thermal conductance is high, comparable to that of graphene-metal covalent-bonded interfaces. Importantly, each interfacial Mo-C bond serves as an independent thermal channel, enabling the modulation of interfacial thermal conductance by controlling Mo vacancy concentration at the interface. The present work provides a viable route for heat management in MoS 2 based electronic devices.2

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Section: In-plane Interfacial Binding Between Mos 2 and Graphenementioning

confidence: 99%

MoS2-graphene in-plane contact for high interfacial thermal conduction

et al. 2017

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“…MD simulation has been widely applied to investigate the thermal transport at GBs. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] By using MD simulation, it is possible to directly observe the independent molecular motion, which has so far been very difficult to obtain through experiments. In addition, the ITR can be interpreted by phonons, which are thermal energy carriers which play an important role when studying nanoscale heat transfer in a superlattice.…”

Section: Introductionmentioning

confidence: 99%

“…The behaviors of phonon scattering at interfaces have been very well studied in the past. 7,[16][17][18][19][20][21][22][23][24][25] Generally, the energy is totally transmitted in a single or perfect crystal. Meanwhile, the phonons are strongly scattered at the GB, where a significant amount of total energy is reflected due to the discontinuity in the structure between two crystals.…”

Section: Introductionmentioning

confidence: 99%

Atomic density effects on temperature characteristics and thermal transport at grain boundaries through a proper bin size selection

Barışık

Kim

2016

The Journal of Chemical Physics

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This study focuses on the proper characterization of temperature profiles across grain boundaries (GBs) in order to calculate the correct interfacial thermal resistance (ITR) and reveal the influence of GB geometries onto thermal transport. The solid-solid interfaces resulting from the orientation difference between the (001), (011), and (111) copper surfaces were investigated. Temperature discontinuities were observed at the boundary of grains due to the phonon mismatch, phonon backscattering, and atomic forces between dissimilar structures at the GBs. We observed that the temperature decreases gradually in the GB area rather than a sharp drop at the interface. As a result, three distinct temperature gradients developed at the GB which were different than the one observed in the bulk solid. This behavior extends a couple molecular diameters into both sides of the interface where we defined a thickness at GB based on the measured temperature profiles for characterization. Results showed dependence on the selection of the bin size used to average the temperature data from the molecular dynamics system. The bin size on the order of the crystal layer spacing was found to present an accurate temperature profile through the GB. We further calculated the GB thickness of various cases by using potential energy (PE) distributions which showed agreement with direct measurements from the temperature profile and validated the proper binning. The variation of grain crystal orientation developed different molecular densities which were characterized by the average atomic surface density (ASD) definition. Our results revealed that the ASD is the primary factor affecting the structural disorders and heat transfer at the solid-solid interfaces. Using a system in which the planes are highly close-packed can enhance the probability of interactions and the degree of overlap between vibrational density of states (VDOS) of atoms forming at interfaces, leading to a reduced ITR. Thus, an accurate understanding of thermal characteristics at the GB can be formulated by selecting a proper bin size. Published by AIP Publishing. [http://dx

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“…Significant progresses have been made recently for studying phonon transmission using atomistic simulation methods, including the phonon wave-packet method 23 based on molecular dynamics simulations, the linear lattice dynamics, 24,25 and the atomistic Green's function (AGF) approach which solves the phonon dynamical equation under the harmonic approximation. In particular, the frequency-dependent phonon transmission across a variety of material interfaces has been studied using the AGF approach, such as the interface in low dimensional atomic chains, 26 strained Si/Ge interface, 27 metal/graphene nanoribbon (GNR) interface, 28 rough interface between two face-centered cubic (FCC) crystals, 29 and more recently across confined material interfaces.…”

Section: Introductionmentioning

confidence: 99%

Effect of lattice mismatch on phonon transmission and interface thermal conductance across dissimilar material interfaces

Yang

2012

Phys. Rev. B

135

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When phonons transport across a material interface, they experience reflection, transmission and mode conversion, which results in a local temperature jump at interface and thus dramatically changes the thermal conductivity of nanostructured materials. Phonon transmission across lattice-matched interfaces has been studied extensively in recent years with the atomistic Green's function (AGF) approach, which usually uses one unit cell to represent the cross-section along the interface. However, modeling phonon transmission across realistic material interfaces is much more challenging because realistic interfaces are usually latticemismatched ones with atomic reconstruction, defects, and species mixing, which demands a larger cross-sectional area for the AGF simulation. In this paper, an integrated molecular dynamics (MD) and AGF approach is developed to study the phonon transmission across latticemismatched interfaces. MD simulation is used to simulate atomic reconstruction close to the 1 Email: Ronggui.Yang@Colorado.Edu interface. The recursive AGF approach is then employed for the first time to calculate frequencydependent phonon transmission across lattice-mismatched interfaces with defects and species mixing, which addresses the numerical challenge in calculating phonon transmission for a relatively large cross-sectional area with reduced computational cost. The study of the relaxed interface formed from two semi-infinite bulk materials shows that lattice mismatch increases the lattice disorder and decreases the adhesion energy, which in turn lowers phonon transmission and reduces the interface thermal conductance across lattice-mismatched interfaces. Low-frequency phonons can be significantly scattered by increasing the defect size across the interface while high frequency phonons can be scattered almost completely (phonon transmission <0.1) across an alloyed layer as thin as 2.27 nm. The effect of lattice-mismatch on phonon transmission becomes smaller for interfaces with defects and species mixing. The effect of annealing temperature on the Si/Ge interface thermal conductance was studied. A significant reduction of the Si/Ge interface thermal conductance was observed for a lattice-mismatched interface when annealed at high temperature, which agrees well with the available experimental data in literature.

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Phonon wave-packet dynamics at semiconductor interfaces by molecular-dynamics simulation

Cited by 314 publications

References 10 publications

MoS2-graphene in-plane contact for high interfacial thermal conduction

MoS2-graphene in-plane contact for high interfacial thermal conduction

Atomic density effects on temperature characteristics and thermal transport at grain boundaries through a proper bin size selection

Effect of lattice mismatch on phonon transmission and interface thermal conductance across dissimilar material interfaces

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