Lattice thermal conductivity of a silicon nanowire under surface stress

Liangruksa, Monrudee; Puri, Ishwar K.

doi:10.1063/1.3583668

Cited by 22 publications

(13 citation statements)

References 37 publications

(42 reference statements)

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“…11 Different methods of reducing the thermal conductivity of SiNWs have been proposed. [12][13][14][15][16][17][18][19] Thin SiNWs with diameters comparable to the dominant phonon wavelength at low temperatures were shown to have low thermal conductivity. 9 While this result is promising, further decrease in the diameter runs into a substantial barrier, due to limitations of fabrication techniques and measurements quantifying the properties of thin nanowires.…”

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confidence: 99%

Significant thermal conductivity reduction of silicon nanowire forests through discrete surface doping of germanium

Pan

Guo

Raja

et al. 2015

Applied Physics Letters

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Silicon nanowires (SiNWs) are promising materials for the realization of highly-efficient and cost effective thermoelectric devices. Reduction of the thermal conductivity of such materials is a necessary and viable pathway to achieve sufficiently high thermoelectric efficiencies, which are inversely proportional to the thermal conductivity. In this article, vertically aligned forests of SiNW and germanium (Ge)-doped SiNW with diameters around 100 nm have been fabricated, and their thermal conductivity has been measured. The results show that discrete surface doping of Ge on SiNW arrays can lead to 23% reduction in thermal conductivity at room temperature compared to uncoated SiNWs. Such reduction can be further enhanced to 44% following a thermal annealing step. By analyzing the binding energy changes of Ge-3d and Si-2p using X-ray photoelectron spectroscopy, we demonstrate that surface doped Ge interacts strongly with Si, enhancing phonon scattering at the Si-Ge interface as has also been shown in non-equilibrium molecular dynamics studies of single nanowires. Overall, our results suggest a viable pathway to improve the energy conversion efficiency of nanowire-forest thermoelectric nanomaterials. V C 2015 AIP Publishing LLC.

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confidence: 99%

Significant thermal conductivity reduction of silicon nanowire forests through discrete surface doping of germanium

Pan

Guo

Raja

et al. 2015

Applied Physics Letters

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“…Using the phononic dispersion, the density of states (DOS) and the ballistic transmission (number of modes at given energy) are calculated as shown in Ref. [16] by: i q i i i q DOS DOS (6) and…”

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confidence: 99%

“…Numerous studies can be found in the literature regarding the thermal conductivity of Si NWs [3,4,5,6,7]. The effects of different scattering mechanisms, i.e.…”

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confidence: 99%

Calculation of Confined Phonon Spectrum in Narrow Silicon Nanowires Using the Valence Force Field Method

Karamitaheri

Neophytou

Taheri

et al. 2013

Journal of Elec Materi

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We study the effect of confinement on the phonon properties of ultra-narrow silicon nanowires of side sizes of 1 10nm . We use the modified valence force field method to compute the phononic dispersion, and extract the density of states, the transmission function, the sound velocity, the ballistic thermal conductance and boundary scatteringlimited diffusive thermal conductivity. We find that the phononic dispersion and the ballistic thermal conductance are functions of the geometrical features of the structures, i.e. the transport orientation and confinement dimension. The phonon group velocity and thermal conductance can vary by a factor of two depending on the geometrical features of the channel. The <110> nanowire has the highest group velocity and thermal conductance, whereas the <111> the lowest. The <111> channel is thus the most suitable orientation for thermoelectric devices based on Si nanowires since it also has a large power factor. Our findings could be useful in the thermal transport design of siliconbased devices for thermoelectric and thermal management applications.

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“…The fixed structures of solids can also be tuned by applying mechanical stress. 1,2 Since incompressible fluids are generally homogeneous, these have been typically ignored for such use. Often it is important to be able to tune such devices for specific applications.…”

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A thermal logic device based on fluid-solid interfaces

Murad¹,

Puri²

2013

Applied Physics Letters

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Thermal rectification requires that thermal conductivity not be a separable function of position and temperature. Investigators have considered inhomogeneous solids to design thermal rectifiers but manipulations of solid lattices are energy intensive. We propose a thermal logic device based on asymmetric solid-fluid resistances that couples two fluid reservoirs separated by solid-fluid interfaces. It is the thermal analog of a three terminal transistor, the hot reservoir being the emitter, the cold reservoir the output, and smaller input reservoirs as the base. Changing the input temperature alters the transport factor and the flux gain as does the base current in a transistor.

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Lattice thermal conductivity of a silicon nanowire under surface stress

Cited by 22 publications

References 37 publications

Significant thermal conductivity reduction of silicon nanowire forests through discrete surface doping of germanium

Significant thermal conductivity reduction of silicon nanowire forests through discrete surface doping of germanium

Calculation of Confined Phonon Spectrum in Narrow Silicon Nanowires Using the Valence Force Field Method

A thermal logic device based on fluid-solid interfaces

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