Size effects in the thermal conductivity of gallium oxide (β-Ga2O3) films grown via open-atmosphere annealing of gallium nitride

2015 ◽  
Vol 117 (8) ◽  
pp. 084308 ◽  
Author(s):  
Chester J. Szwejkowski ◽  
Nicole C. Creange ◽  
Kai Sun ◽  
Ashutosh Giri ◽  
Brian F. Donovan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Gallium Nitride ◽  
Size Effects ◽  
Gallium Oxide ◽  
Open Atmosphere

Onset of size effects in lattice thermal conductivity and lifetime of low-frequency thermal phonons

2012 ◽  
Vol 1404 ◽  
Author(s):  
A.A. Maznev
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Size Effects ◽  
Lattice Thermal Conductivity ◽  
Low Frequency ◽  
Square Root ◽  
Relaxation Rates ◽  
Frequency Limit ◽  
Conductivity Of Thin Films ◽  
Closed Form Formula

ABSTRACTThe onset of size effects in phonon-mediated thermal transport along a thin film at temperatures comparable or greater than the Debye temperature is analyzed theoretically. Assuming a quadratic frequency dependence of phonon relaxation rates in the low-frequency limit, a simple closed-form formula for the reduction of the in-plane thermal conductivity of thin films is derived. The effect scales as the square root of the film thickness, which leads to the prediction of measurable size-effects even at “macroscopic” distances ~100 μm. However, this prediction needs to be corrected to account for the deviation from the ω−2 dependence of phonon lifetimes at sub-THz frequencies due to the transition from Landau-Rumer to Akhiezer mechanism of phonon dissipation.

scholarly journals Lattice Boltzmann method simulation of the gas heat conduction of nanoporous material

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3749-3756
Author(s):  
Ya Han ◽  
Shuai Li ◽  
Hai-Dong Liu ◽  
Weipeng Cui
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Lattice Boltzmann Method ◽  
Knudsen Number ◽  
Lattice Boltzmann ◽  
Size Effects ◽  
Temperature Jump ◽  
Boundary Scattering ◽  
Nanoporous Material ◽  
Boltzmann Method

In order to deeply investigate the gas heat conduction of nanoporous aerogel, a model of gas heat conduction was established based on microstructure of aerogel. Lattice Boltzmann method was used to simulate the temperature distribution and gas thermal conductivity at different size, and the size effects of gas heat conduction have had been obtained under micro-scale conditions. It can be concluded that the temperature jump on the boundary was not obvious and the thermal conductivity remained basically constant when the value of Knudsen number was less than 0.01; as the value of Knudsen number increased from 0.01 to 0.1, there was a clear temperature jump on the boundary and the thermal conductivity tended to decrease and the effect of boundary scattering increased drastically, as the value of Knudsen number was more than 0.1, the temperature jump increased significantly on the boundary, furtherly, the thermal conductivity decreased dramatically, and the size effects were significantly.

Size effects on the thermal conductivity of polycrystalline platinum nanofilms

2006 ◽  
Vol 18 (34) ◽  
pp. 7937-7950 ◽  
Author(s):  
Q G Zhang ◽  
B Y Cao ◽  
X Zhang ◽  
M Fujii ◽  
K Takahashi
Keyword(s):  
Thermal Conductivity ◽  
Size Effects ◽  
Polycrystalline Platinum

Short channel effects on gallium nitride/gallium oxide nanowire transistors

2012 ◽  
Vol 101 (18) ◽  
pp. 183501 ◽  
Author(s):  
J.-W. Yu ◽  
P.-C. Yeh ◽  
S.-L. Wang ◽  
Y.-R. Wu ◽  
M.-H. Mao ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Gallium Oxide ◽  
Short Channel Effects ◽  
Short Channel ◽  
Nanowire Transistors ◽  
Channel Effects

scholarly journals Anisotropic thermal conductivity in single crystal β-gallium oxide

2015 ◽  
Vol 106 (11) ◽  
pp. 111909 ◽  
Author(s):  
Zhi Guo ◽  
Amit Verma ◽  
Xufei Wu ◽  
Fangyuan Sun ◽  
Austin Hickman ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Single Crystal ◽  
Gallium Oxide ◽  
Anisotropic Thermal Conductivity

scholarly journals Grain-size effects on the thermal conductivity of nanosolids

2016 ◽  
Vol 10 (3) ◽  
pp. 375-380 ◽  
Author(s):  
Madan Singh ◽  
Kopang Khotso Hlabana ◽  
Sanjay Singhal ◽  
Kamal Devlal
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Size Effects ◽  
Grain Size Effects

Size Effects on Nonequilibrium Laser Heating of Metal Films

1993 ◽  
Vol 115 (4) ◽  
pp. 842-847 ◽  
Author(s):  
T. Q. Qiu ◽  
C. L. Tien
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Size Effects ◽  
Laser Heating ◽  
Energy Exchange ◽  
Short Pulse ◽  
Heating Process ◽  
Metal Thin Films ◽  
Short Pulse Laser

Picosecond and sub-picosecond lasers have become important tools in the fabrication and study of microstructures. When the laser pulse duration becomes comparable with or less than the characteristic time of energy exchange among microscopic energy carriers, the excited carriers are no longer in thermal equilibrium with the other carriers, creating a nonequilibrium heating situation. The presence of interfaces in metals provides additional scattering processes for electrons, which in turn affects the nonequilibrium heating process. This work studies size effects, due to both surface scattering and grain-boundary scattering, on the thermal conductivity and the energy exchange between electrons and the material lattice. A simple formula is established to predict the influence of film thickness, grain size, interface scattering parameters, and the electron and lattice temperatures on the effective thermal conductivity of metal thin films. Predictions of the analysis agree with the available experimental data. A three-energy-level model is developed to characterize the energy exchange between electrons and the lattice. This study shows that the size effect reduces the effective thermal conductivity and increases the electron-phonon energy exchange rate. The results are useful for improving processing quality, interpreting diagnostic results, and preventing thermal damage of thin films during short-pulse laser heating.

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