Joule Heating and Thermal Conductivity Determination of Nanoscale Metallic Thin Films and Interconnects

2005 ◽  
Author(s):  
Siva P. Gurrum ◽  
William P. King ◽  
Yogendra K. Joshi ◽  
Koneru Ramakrishna
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Free Path ◽  
Joule Heating ◽  
High Performance ◽  
Effective Conductivity ◽  
Mean Free Path ◽  
Current Crowding ◽  
Metal Line ◽  
Thin Metallic Film

Evolution of high performance microprocessors has resulted in a steady decrease in on-chip feature sizes. Increasing requirements on maximum current density are expected to increase interconnect temperature drastically due to Joule heating. As interconnect dimensions approach the electron mean free path range, effective conductivity reduces due to size effects. Thermal characterization of sub-micron interconnects and thin films is thus highly important. This work investigates current crowding and the associated Joule heating near a constriction in a thin metallic film and proposes a novel technique to determine thermal conductivity of thin metallic films and interconnects in the sub-100 nm range. Scanning Joule Expansion Microscopy (SJEM) measures the thermal expansion of the structure whose thickness is comparable to the mean free path of electrons. Numerical solution of heat conduction equation in the frequency space is used to obtain a fit for effective thermal conductivity. A thermal conductivity of ~ 80.0 W/mK provides a best fit to the data. This is about one-third the bulk thermal conductivity of gold, which is 318 W/mK at room temperature. Using Wiedemann-Franz Law a thermal conductivity of 92.0 W/mK is obtained after measuring the electrical resistivity of the metal line. This is close to that obtained through numerical fit.

Lattice Boltzmann Modeling of Phonon Heat Conduction in Superlattice Structures

2010 ◽  
Author(s):  
Cristian J. San Marti´n ◽  
Amador M. Guzma´n ◽  
Rodrigo A. Escobar
Keyword(s):  
Thermal Conductivity ◽  
Free Path ◽  
Lattice Boltzmann ◽  
Phonon Dispersion ◽  
Effective Conductivity ◽  
Mean Free Path ◽  
One Dimension ◽  
The Mean ◽  
Superlattice Structures ◽  
Boltzmann Method

The results of temperature prediction and determination of effective thermal conductivity in periodic Si-Ge superlattice in one dimension, at length scale comparable to the mean free path are presented. Classical heat transfer models such as Fourier’s law do not represent what actually happens within electronic devices at these length scales. Phonon-border and phonon-interface scattering effects provide discontinuous jumps in temperature distribution when the mean free path is comparable with the device’s characteristic length, a relation given by the Knudsen number (Kn). For predicting the temperature within the periodic Si-Ge superlattice use is made of the lattice Boltzmann method in one dimension, using Debye’s model in the phonon dispersion relation. The predictions show that as Kn increases, so do the jumps at the borders, the same as at the interfaces. The prediction also shows that the effective conductivity of the Si-Ge superlattice decreases as Kn and the number of layers of material increase, and that keff decreases as the magnitude of p increases, a factor that allows heat flow between one layer and another. Use of gray LBM leads to good approximations of the actual temperature field and thermal conductivity values for the superlattice materials model when the physics of phonons established by Debye’s model is used.

Electron effective mean free path and thermal conductivity predictions of metallic thin films

2008 ◽  
Vol 92 (17) ◽  
pp. 171910 ◽  
Author(s):  
Jae Sik Jin ◽  
Joon Sik Lee ◽  
Ohmyoung Kwon
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Free Path ◽  
Mean Free Path ◽  
Metallic Thin Films

Ioffe–Regel limit and lattice thermal conductivity reduction of high performance (AgSbTe2)15(GeTe)85 thermoelectric materials

2014 ◽  
Vol 2 (9) ◽  
pp. 3251-3256 ◽  
Author(s):  
Tiejun Zhu ◽  
Hongli Gao ◽  
Yi Chen ◽  
Xinbing Zhao
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Free Path ◽  
Thermoelectric Materials ◽  
High Performance ◽  
Lattice Thermal Conductivity ◽  
State Of The Art ◽  
Mean Free Path ◽  
Lattice Parameter ◽  
Fine Grained

This work shows that the carrier mean free path of TAGS-85 thermoelectric materials is comparable to the lattice parameter, and that refining the grain size will not affect the mobility while benefiting the thermal conductivity reduction. A state-of-the-art ZT of ~ 1.6 is obtained for the fine-grained samples.

scholarly journals Ballistic Heat Transport in Nanocomposite: The Role of the Shape and Interconnection of Nanoinclusions

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1982
Author(s):  
Paul Desmarchelier ◽  
Alice Carré ◽  
Konstantinos Termentzidis ◽  
Anne Tanguy
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Free Path ◽  
Mean Free Path ◽  
Strong Increase ◽  
Moderate Increase ◽  
Energy Propagation ◽  
The Mean ◽  
Dynamics Simulations

In this article, the effect on the vibrational and thermal properties of gradually interconnected nanoinclusions embedded in an amorphous silicon matrix is studied using molecular dynamics simulations. The nanoinclusion arrangement ranges from an aligned sphere array to an interconnected mesh of nanowires. Wave-packet simulations scanning different polarizations and frequencies reveal that the interconnection of the nanoinclusions at constant volume fraction induces a strong increase of the mean free path of high frequency phonons, but does not affect the energy diffusivity. The mean free path and energy diffusivity are then used to estimate the thermal conductivity, showing an enhancement of the effective thermal conductivity due to the existence of crystalline structural interconnections. This enhancement is dominated by the ballistic transport of phonons. Equilibrium molecular dynamics simulations confirm the tendency, although less markedly. This leads to the observation that coherent energy propagation with a moderate increase of the thermal conductivity is possible. These findings could be useful for energy harvesting applications, thermal management or for mechanical information processing.

Experiments on the flow of heat in liquid helium below 0.7 °K

1958 ◽  
Vol 246 (1246) ◽  
pp. 390-405 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Liquid Helium ◽  
Free Path ◽  
Empirical Relation ◽  
Mean Free Path ◽  
Series Of Experiments ◽  
The Mean ◽  
Set Up ◽  
Low Pressures ◽  
Measured Thermal Conductivity

A series of experiments has been performed to study the steady flow of heat in liquid helium in tubes of diameter 0.05 to 1.0 cm at temperatures between 0.25 and 0.7 °K. The results are interpreted in terms of the flow of a gas of phonons, in which the mean free path λ varies with temperature, and may be either greater or less than the diameter of the tube d . When λ ≫ d the flow is limited by the scattering of the phonons at the walls, and the effect of the surface has been studied, but when λ ≪ d viscous flow is set up in which the measured thermal conductivity is increased above that for wall scattering. This behaviour is very similar to that observed in the flow of gases at low pressures, and by applying kinetic theory to the problem it can be shown that the mean free path of the phonons characterizing viscosity can be expressed by the empirical relation λ = 3.8 x 10 -3 T -4.3 cm. This result is inconsistent with the temperature dependence of λ as T -9 predicted theoretically by Landau & Khalatnikov (1949).

scholarly journals Effect of Grain Size and Film Thickness on the Thermoelectric Properties of Flexible Sb2Te3 Thin Films

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Pornsiri Wanarattikan ◽  
Piya Jitthammapirom ◽  
Rachsak Sakdanuphab ◽  
Aparporn Sakulkalavek
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Film Thickness ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Flexible Substrate ◽  
Rf Magnetron Sputtering ◽  
Mean Free Path

In this work, stoichiometric Sb2Te3 thin films with various thicknesses were deposited on a flexible substrate using RF magnetron sputtering. The grain size and thickness effects on the thermoelectric properties, such as the Seebeck coefficient (S), electrical conductivity (σ), power factor (PF), and thermal conductivity (k), were investigated. The results show that the grain size was directly related to film thickness. As the film thickness increased, the grain size also increased. The Seebeck coefficient and electrical conductivity corresponded to the grain size of the films. The mean free path of carriers increases as the grain size increases, resulting in a decrease in the Seebeck coefficient and increase in electrical conductivity. Electrical conductivity strongly affects the temperature dependence of PF which results in the highest value of 7.5 × 10−4 W/m·K2 at 250°C for film thickness thicker than 1 µm. In the thermal conductivity mechanism, film thickness affects the dominance of phonons or carriers. For film thicknesses less than 1 µm, the behaviour of the phonons is dominant, while both are dominant for film thicknesses greater than 1 µm. Control of the grain size and film thickness is thus critical for controlling the performance of Sb2Te3 thin films.

Significantly enhanced phonon mean free path and thermal conductivity by percolation of silver nanoflowers

2019 ◽  
Vol 21 (5) ◽  
pp. 2453-2462 ◽  
Author(s):  
Daewoo Suh ◽  
Sanghoon Lee ◽  
Chenchen Xu ◽  
Agha Aamir Jan ◽  
Seunghyun Baik
Keyword(s):  
Thermal Conductivity ◽  
Free Path ◽  
Mean Free Path ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Interface Materials ◽  
Polyurethane Matrix ◽  
Percolation Network

A percolation network of silver nanoflowers dramatically increased the thermal conductivity (42.4 W m−1 K−1) in soft polyurethane-matrix thermal interface materials.

Thermal Conductivity of Single-Crystal and Sintered RBa2Cu3O7 at low Temperatures

1987 ◽  
Vol 99 ◽  
Author(s):  
J. E. Graebner ◽  
L. F. Schneemeyer ◽  
R. J. Cava ◽  
J. V. Waszczak ◽  
E. A. Rietman
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Single Crystals ◽  
Free Path ◽  
Low Temperatures ◽  
Rayleigh Scattering ◽  
Resonant Scattering ◽  
Sintered Sample ◽  
Mean Free Path ◽  
Strong Scattering

ABSTRACTThe thermal conductivity k of micro-twinned single crystals of YBa2Cu3O7 and HoBa2Cu3O7 and a sintered sample of YBa2Cu3O7 has been measured for temperatures 0.03<T<5K. For the single crystals, k is small and varies as T1.8-1.9 This behavior resembles k for glassy insulators except for the lack of a plateau above IK. It is concluded that the thermal carriers are phonons with their mean free path limited by resonant scattering from tunneling entities, as in glasses. Suggestions for the location of tunneling systems are given. For the sinter, k is still smaller but does not follow a power law T-dependence. It is similar to other sintered ceramics with the same particle size, where the phonon mean free path is dominated by Rayleigh scattering from the particles. This strong scattering from the microstructure presumably masks the scattering from TS within each particle.

Beating the Thermal Conductivity of Air Using Packed Nanoparticle Bed

2006 ◽  
Author(s):  
Ravi Prasher
Keyword(s):  
Thermal Conductivity ◽  
Surface Energy ◽  
Effective Thermal Conductivity ◽  
Free Path ◽  
Packed Bed ◽  
Mean Free Path ◽  
Low Thermal Conductivity ◽  
Pressure Surface

Thermal conductivity of packed bed of nanoparticles is calculated in this paper. Results show that effective thermal conductivity of nanoparticle bed can be very low. Thermal conductivity of the nanoparticle bed can be smaller than the thermal conductivity of air. Thermal conductivity depends on pressure, surface energy of the nanoparticle, and phonon mean free path.

Sign in / Sign up

Export Citation Format

Share Document