scholarly journals Thermal Transport in Silicon-Germanium Superlattices at Low Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Zan Wang ◽  
Xingyu Cai ◽  
Tiezhu Mao
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Inelastic Scattering ◽  
Silicon Germanium ◽  
Thermal Transport ◽  
Low Temperatures ◽  
Heterogeneous Materials ◽  
Elastic And Inelastic Scattering ◽  
Debye Temperatures ◽  
Thermal Conductivities

Interfacial thermal resistances between heterogeneous materials are still a challengeable subject since the mechanism to explain it quantitatively is not clear in spite of its importance. We propose a Monte Carlo (MC) model to study phonon interfacial elastic and inelastic scattering behaviors for superlattices composed of Si and Ge materials, which substantially reduces the amount of computations. In particular, below Debye temperatures, the molecular dynamics (MD) solution is not precise enough for semiconductors because of quantization errors. In this work, thermal conductivities and thermal rectifications of Si/Ge and Ge/Si superlattices with different periods are investigated separately at temperatures below 200 K.

In-plane thermal transport in black phosphorene/graphene layered heterostructures: a molecular dynamics study

2018 ◽  
Vol 20 (32) ◽  
pp. 21151-21162 ◽  
Author(s):  
Ting Liang ◽  
Ping Zhang ◽  
Peng Yuan ◽  
Siping Zhai
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Thermal Transport ◽  
Single Layer ◽  
Black Phosphorene ◽  
Non Equilibrium Molecular Dynamics ◽  
Dynamics Simulations ◽  
Non Equilibrium ◽  
Thermal Conductivities

We use non-equilibrium molecular dynamics simulations to study the in-plane thermal conductivities of black phosphorene/graphene heterostructures and single-layer black phosphorene in black phosphorene/graphene heterostructures.

scholarly journals Molecular Dynamics Simulations of the Thermal Conductivity of Silicon-Germanium and Silicon-Germanium-Tin Alloys

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Zan Wang ◽  
X. Y. Cai ◽  
W. K. Zhao ◽  
H. Wang ◽  
Y. W. Ruan
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Silicon Germanium ◽  
Nonequilibrium Molecular Dynamics ◽  
Tin Alloys ◽  
Penetration Distance ◽  
Germanium Tin ◽  
Dynamics Simulations ◽  
Thermal Conductivities

In this work, we investigate the thermal conductivity properties of Si 1 − x Ge x and Si 0.8 Ge 0 Sn 2 y alloys. The equilibrium molecular dynamics (EMD) is employed to calculate the thermal conductivities of Si 1 − x Ge x alloys when x is different at temperatures ranging from 100 K to 1100 K. Then nonequilibrium molecular dynamics (NEMD) is used to study the relationships between y and the thermal conductivities of Si 0.8 Ge 0.2 Sn 2 y alloys. In this paper, Ge atoms are randomly doped, and tin atoms are doped in three distributing ways: random doping, complete doping, and bridge doping. The results show that the thermal conductivities of Si 1 − x Ge x alloys decrease first, then increase with the rise of x , and reach the lowest value when x changes from 0.4 to 0.5. No matter what the value of x is, the thermal conductivities of Si 1 − x Ge x alloys decrease with the increase of temperature. Thermal conductivities of Si 0.8 Ge 0.2 alloys can be significantly inhibited by doping an appropriate number of Sn atoms. For the random doping model, thermal conductivities of Si 0.8 Ge 0.2 Sn y alloys approach the lowest level when y is 0.10. Whether it is complete doping or bridge doping, thermal conductivities decrease with the increase of the number of doped layers. In addition, in the bridge doping model, both the number of Sn atoms in the [001] direction and the penetration distance of Sn atoms strongly influence thermal conductivities. The thermal conductivities of Si 0.8 Ge 0.2 Sn y alloys are positively associated with the number of Sn atoms in the [001] direction and the penetration distance of Sn atoms.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

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