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Title: Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity

Abstract

By studying the temperature-dependent behavior (300 K down to 43 K) of electron thermal conductivity (κ) in a 3.2 nm-thin Ir film, we quantify the extremely confined defect-electron scatterings and isolate the intrinsic phonon-electron scattering that is shared by the bulk Ir. At low temperatures below 50 K, κ of the film has almost two orders of magnitude reduction from that of bulk Ir. The film has ∂κ/∂T > 0, while the bulk Ir has ∂κ/∂T < 0. We introduce a unified thermal resistivity (Θ = T/κ) to interpret these completely different κ ∼ T relations. It is found that the film and the bulk Ir share a very similar Θ ∼ T trend, while they have a different residual part (Θ{sub 0}) at 0 K limit: Θ{sub 0} ∼ 0 for the bulk Ir, and Θ{sub 0} = 5.5 m·K{sup 2}/W for the film. The Ir film and the bulk Ir have very close ∂Θ/∂T (75–290 K): 6.33 × 10{sup −3} m K/W for the film and 7.62 × 10{sup −3} m K/W for the bulk Ir. This strongly confirms the similar phonon-electron scattering in them. Therefore, the residual thermal resistivity provides an unprecedented way to quantitatively evaluating defect-electron scattering (Θ{sub 0}) in heat conduction. Moreover, the interfacial thermal conductance across the grain boundaries is found larger than that of Al/Cu interface, and itsmore » value is proportional to temperature, largely due to the electron's specific heat. A unified interfacial thermal conductance is also defined and firmly proves this relation. Additionally, the electron reflection coefficient is found to be large (88%) and almost temperature independent.« less

Authors:
; ;  [1];  [1];  [2]
  1. Department of Mechanical Engineering, Iowa State University, 2010 Black Engineering Building, Ames, Iowa 50011 (United States)
  2. (China)
Publication Date:
OSTI Identifier:
22412830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM; COPPER; ELECTRONS; FILMS; GRAIN BOUNDARIES; INTERFACES; IRIDIUM; PHONONS; REFLECTION; SCATTERING; SPECIFIC HEAT; TEMPERATURE DEPENDENCE; THERMAL CONDUCTION; THERMAL CONDUCTIVITY

Citation Formats

Cheng, Zhe, Xu, Zaoli, Xu, Shen, Wang, Xinwei, E-mail: xwang3@iastate.edu, and School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209. Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity. United States: N. p., 2015. Web. doi:10.1063/1.4905607.
Cheng, Zhe, Xu, Zaoli, Xu, Shen, Wang, Xinwei, E-mail: xwang3@iastate.edu, & School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209. Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity. United States. doi:10.1063/1.4905607.
Cheng, Zhe, Xu, Zaoli, Xu, Shen, Wang, Xinwei, E-mail: xwang3@iastate.edu, and School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209. Wed . "Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity". United States. doi:10.1063/1.4905607.
@article{osti_22412830,
title = {Temperature dependent behavior of thermal conductivity of sub-5 nm Ir film: Defect-electron scattering quantified by residual thermal resistivity},
author = {Cheng, Zhe and Xu, Zaoli and Xu, Shen and Wang, Xinwei, E-mail: xwang3@iastate.edu and School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209},
abstractNote = {By studying the temperature-dependent behavior (300 K down to 43 K) of electron thermal conductivity (κ) in a 3.2 nm-thin Ir film, we quantify the extremely confined defect-electron scatterings and isolate the intrinsic phonon-electron scattering that is shared by the bulk Ir. At low temperatures below 50 K, κ of the film has almost two orders of magnitude reduction from that of bulk Ir. The film has ∂κ/∂T > 0, while the bulk Ir has ∂κ/∂T < 0. We introduce a unified thermal resistivity (Θ = T/κ) to interpret these completely different κ ∼ T relations. It is found that the film and the bulk Ir share a very similar Θ ∼ T trend, while they have a different residual part (Θ{sub 0}) at 0 K limit: Θ{sub 0} ∼ 0 for the bulk Ir, and Θ{sub 0} = 5.5 m·K{sup 2}/W for the film. The Ir film and the bulk Ir have very close ∂Θ/∂T (75–290 K): 6.33 × 10{sup −3} m K/W for the film and 7.62 × 10{sup −3} m K/W for the bulk Ir. This strongly confirms the similar phonon-electron scattering in them. Therefore, the residual thermal resistivity provides an unprecedented way to quantitatively evaluating defect-electron scattering (Θ{sub 0}) in heat conduction. Moreover, the interfacial thermal conductance across the grain boundaries is found larger than that of Al/Cu interface, and its value is proportional to temperature, largely due to the electron's specific heat. A unified interfacial thermal conductance is also defined and firmly proves this relation. Additionally, the electron reflection coefficient is found to be large (88%) and almost temperature independent.},
doi = {10.1063/1.4905607},
journal = {Journal of Applied Physics},
number = 2,
volume = 117,
place = {United States},
year = {Wed Jan 14 00:00:00 EST 2015},
month = {Wed Jan 14 00:00:00 EST 2015}
}