Thermal Conductivity Anisotropy in Phonon Transport of Bi2Te3/Bi0.5Sb1.5Te3 Superlattice Film

2020 ◽  
Vol 15 (4) ◽  
pp. 463-467
Author(s):  
Soo-Young Kang ◽  
No-Won Park ◽  
Won-Yong Lee ◽  
Min-Sung Kang ◽  
Gil-Sung Kim ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Electron Scattering ◽  
Phonon Scattering ◽  
Phonon Transport ◽  
Temperature Dependent ◽  
Conductivity Anisotropy ◽  
Large Anisotropy ◽  
Temperature Dependent Thermal Conductivity ◽  
Thermal Conductivities

Nanoscale superlattice thin films generally exhibit larger phonon and electron scattering at the interface in the direction of the cross-plane of the samples. Therefore, it is very important to further detailed study of especially phonon transport of the superlattice films. Here, we report temperature dependent thermal conductivity anisotropy in phonon transport of Bi2 Te3 /Bi0.5 Sb1.5 Te3 superlattice thin films at 200–500 K. Thermal conductivity of these thin films for in- and cross-plane thermal conductivities were determined to be approximately 0.74 and 0.4 W m–1 K–1 at 200–500 K, respectively, clearly indicating ∼185% suppression in- and cross-plane thermal conductivities of the superlattice thin films with a large anisotropic behavior. Such large anisotropy in the thermal conductivity can be attributed to enhanced phonon scattering occurring at the interface of the Bi2Te3 and Bi0.5Sb1.5Te3 layer.

Thermal Conductivity of Nano-Porous Bismuth Thin Films for Thermoelectric Applications

1999 ◽  
Author(s):  
David W. Song ◽  
Wei-Ning Shen ◽  
Taofang Zeng ◽  
Weili Liu ◽  
Gang Chen ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Phonon Transport ◽  
Porous Films ◽  
Temperature Dependent ◽  
Si Substrates ◽  
Order Of Magnitude ◽  
Metal Organic ◽  
Temperature Dependent Thermal Conductivity

Abstract Good thermoelectric materials require a small thermal conductivity while maintaining a high electrical conductivity and Seebeck coefficient. Nano-porous systems provide one possible route of increasing the thermoelectric figure-of-merit by disturbing phonon transport more than electron transport. In this work, the temperature dependent thermal conductivity of nano-porous bismuth thin films was measured. Thin Bi films of various porosity and thickness were deposited by metal-organic deposition onto Si substrates. The thermal conductivity of Bi films was measured using a differential 3-ω method, in which the temperature rise across a Bi film was experimentally measured and used to calculate its thermal conductivity. Experimental results show an order-of-magnitude reduction in the porous Bi thin film thermal conductivity due to nano-pores compared to non-porous films. The drastic reduction in thermal conductivity cannot be explained by available models on the thermal conductivity of porous media.

Performance Analysis of Micro-Raman Spectroscopy Models for Thermal Conductivity Calculation

2021 ◽  
Author(s):  
Taher Meydando ◽  
Nazli Donmezer
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Phonon Scattering ◽  
Raman Laser ◽  
Current Approach ◽  
Slab Model ◽  
Boltzmann Transport ◽  
Micro Raman Spectroscopy ◽  
Thermal Conductivities

Abstract Micro-Raman spectroscopy has been preferred recently to measure the thermal conductivity of thin-films due to its nondestructive and non-contact nature. However, the thermal size effects originating from both localized heat generation from Raman laser and phonon scattering at boundaries may cause erroneous estimation of the thermal conductivities with the current approach. In this study, the gray phonon Boltzmann transport equation (BTE) is solved to improve the results of micro-Raman thermal conductivity measurements. Due to the frequency independence of single phonon mode in the gray BTE model, our method stays ahead of most theoretical methods in calculation time while giving adequate agreement with the literature data. The improved thermal conductivities are evaluated at various laser powers and focal lengths. Subsequently, the values of thermal conductivities are compared with a simple slab model in which the deduction of thermal conductivity in sub-micron thicknesses is calculated using reduced heat flux through the slab resulting from phonon directional energy densities. The results show that subsequent errors are present in measuring the thermal conductivity of relatively thick, thin films with this technique which are noticed by comparing with the simple slab model. Finally, a virtual micro-Raman thermography experiment is developed, and its validity is verified by the same slab model.

Thermal Conductivity of Nano-Porous Bismuth Antimony Telluride

2010 ◽  
Author(s):  
Saburo Tanaka ◽  
Masayuki Takashiri ◽  
Koji Miyazaki
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Antimony Telluride ◽  
Bismuth Antimony Telluride ◽  
Porous Thin Films ◽  
Average Grain Size ◽  
Bismuth Antimony ◽  
Bulk Alloys ◽  
Thermal Conductivities

Bismuth antimony telluride (Bi0.4Te3.0Sb1.6) nano-porous thin films have been prepared and measured their thermal conductivities. The thin films exhibit an average grain size of 50 nm and random crystal orientation. The cross-plane thermal conductivity is measured by a differential 3ω method at temperature range from 100 to 300 K, and the determined thermal conductivities are from 0.09 to 0.18 W/(m·K). As compared with bulk alloys at the same atomic composition, the nano-porous thin films exhibit an eightfold reduction in the thermal conductivity. For more detail analysis, the reduction of the thermal conductivity is examined by a simplified phonon gas model on a single crystal of bulk Bi2Te3. The analytical model fairly agreed with the experimental results, and thus we consider that the thermal conductivity is reduced by the strong phonon scattering at the nano-pores.

Cross-plane temperature-dependent thermal conductivity of Al-doped zinc oxide thin films

2015 ◽  
Vol 638 ◽  
pp. 83-87 ◽  
Author(s):  
Tae-Hyun Park ◽  
No-Won Park ◽  
Jinhwan Kim ◽  
Won-Yong Lee ◽  
Jung-Hyuk Koh ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Zinc Oxide ◽  
Oxide Thin Films ◽  
Temperature Dependent ◽  
Plane Temperature ◽  
Temperature Dependent Thermal Conductivity

scholarly journals Temperature dependent thermal conductivity of pure silica MEL and MFI zeolite thin films

2012 ◽  
Vol 111 (5) ◽  
pp. 054910 ◽  
Author(s):  
Jin Fang ◽  
Yi Huang ◽  
Christopher M. Lew ◽  
Yushan Yan ◽  
Laurent Pilon
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Mfi Zeolite ◽  
Temperature Dependent ◽  
Pure Silica ◽  
Temperature Dependent Thermal Conductivity

scholarly journals Reduced temperature-dependent thermal conductivity of magnetite thin films by controlling film thickness

2014 ◽  
Vol 9 (1) ◽  
pp. 96 ◽  
Author(s):  
No-Won Park ◽  
Won-Yong Lee ◽  
Jin-A Kim ◽  
Kyungjun Song ◽  
Hyuneui Lim ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Film Thickness ◽  
Temperature Dependent ◽  
Reduced Temperature ◽  
Temperature Dependent Thermal Conductivity

Impact on Thermal Conductivities of Nanostructured Bismuth Telluride Based Thin Films

2011 ◽  
Author(s):  
Saburo Tanaka ◽  
Masayuki Takashiri ◽  
Koji Miyazaki
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Bismuth Telluride ◽  
Phonon Scattering ◽  
Omega Method ◽  
Average Grain Size ◽  
3 Omega ◽  
Bulk Alloys ◽  
Nanocrystalline Thin Films ◽  
Thermal Conductivities

Nanostructured bismuth telluride based thin films, including nanoparticle and nanocrystalline have been prepared and measured their thermal conductivities. These thin films exhibit an average grain size of from 10 nm to 150 nm. The cross-plane thermal conductivities are measured by 3-omega method at 300 K. The determined nanostructured bismuth telluride thermal conductivities are 0.18 W/(m·K) and nanoparticle bismuth telluride thin film thermal conductivities are from 0.61 W/(m·K) to 0.80 W/(m·K). As compared with bulk alloys at the same atomic composition, both the nanoparticle and nanocrystalline thin films exhibit a reduction in the thermal conductivity. For more detail analysis, the reduction of the thermal conductivity is examined by a simplified phonon gas model on single crystal of bulk bismuth telluride, antimony telluride and bismuth selenide, The analytical model is consistent with the experimental results, and thus we consider that the thermal conductivity is reduced by the strong phonon scattering.

Sign in / Sign up

Export Citation Format

Share Document