Anisotropy and boundary scattering in the lattice thermal conductivity of silicon nanomembranes

2010 ◽  
Vol 82 (4) ◽  
Author(s):  
Z. Aksamija ◽  
I. Knezevic
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Boundary Scattering ◽  
Silicon Nanomembranes

LATTICE THERMAL CONDUCTIVITY IN A HOLLOW SILICON NANOWIRE

2005 ◽  
Vol 19 (06) ◽  
pp. 1017-1027 ◽  
Author(s):  
WEI-QING HUANG ◽  
KE-QIU CHEN ◽  
Z. SHUAI ◽  
LINGLING WANG ◽  
WANGYU HU
Keyword(s):  
Thermal Conductivity ◽  
Relaxation Time ◽  
Lattice Thermal Conductivity ◽  
Silicon Nanowire ◽  
Boundary Scattering ◽  
Phonon Confinement ◽  
Time Approximation ◽  
Si Nanowire ◽  
Scattering Mechanisms ◽  
Relaxation Time Approximation

We theoretically investigate the lattice thermal conductivity of a hollow Si nanowire under the relaxation time approximation. The results show that the thermal conductivity in such structure is decreased markedly below the bulk value due to phonon confinement and boundary scattering. The thermal conductivities under different scattering mechanisms are given, and it is found that the boundary scattering is dominant resistive process for the decrease of the thermal conductivity.

Thermal Conductivity of N-Type Si-Ge

1991 ◽  
Vol 234 ◽  
Author(s):  
Paul G. Klfmens
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundary ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Electronic Conductivity ◽  
Boundary Scattering ◽  
Low Frequencies ◽  
Free Carriers ◽  
Anharmonic Interactions ◽  
Debye Frequency

ABSTRACTThe lattice thermal conductivity of 80-20 Si-Ge is treated theoretically for the case of the Fermi energy positioned for optimum figure of merit. The spectral distribution of the lattice conductivity is limited by anharmonic interactions, by the randomness of the Si-Ge lattice and, at low frequencies, by the interaction with free carriers and neutral donors. The two latter processes dominate over grain boundary scattering. The spectral conductivity is sharply peaked around 0.1 of the Debye frequency. A further reduction in lattice conductivity can be obtained by small insulating inclusions. This is partially offset by a reduction in electronic conductivity, but results in some improvement in the figure of merit.

A Two-Temperature Model of Narrow-Body Silicon Transistors Under Steady State and Transient Operation

2008 ◽  
Author(s):  
Zhun-Yong Ong ◽  
Eric Pop
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Energy Transfer ◽  
Steady State ◽  
Lattice Thermal Conductivity ◽  
Boundary Scattering ◽  
Temperature Model ◽  
Acoustic Phonons ◽  
Silicon Thin Films ◽  
Two Temperature

We present a simple theory of diffusive phonon heat transport in silicon thin films using the Two-Temperature Model (TTM). In silicon thin films, boundary scattering reduces the lifetime and hence, the mean free path of acoustic phonons. As acoustic phonons are responsible for heat transport in silicon, the latter effect leads to a reduction in the lattice thermal conductivity. However, optical phonons are unaffected by boundary scattering. As the boundary scattering rate exceeds the inverse lifetime of acoustic phonons and the energy relaxation rate between optical and acoustic phonons, it results in an energy transfer bottleneck. The reduced lattice thermal conductivity from boundary scattering and the energy transfer bottleneck are taken into account in the TTM. We apply the TTM to find the steady temperature distribution in a 2D model of a silicon-on-insulator (SOI) device. The numerical results are in good agreement with those obtained from the more sophisticated full dispersion model of the Boltzmann Transport Equation (BTE). We apply the TTM to calculate the steady state and transient temperature distributions in a simplified 1D model of a SOI device.

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