The Nature of Silicon Nanowire Roughness and Thermal Conductivity Suppression by Phonon Scattering Mechanisms

Glynn, Colm; Jones, Kim-Marie; Mogili, Vishnu; McSweeney, William; O’Dwyer, Colm

doi:10.1149/2.0071703jss

Cited by 12 publications

(4 citation statements)

References 45 publications

(82 reference statements)

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“…The broadening of Raman FWHM is a result of opposite peak shifts of the F 2g mode induced by the tensile and compressive strains in the inner and outer bending regions. 59 It also represents a reduction of phonon mean free path 60 and phonon lifetime. 61,62 Similar to HRTEM and electron diffraction results, the FWHM of the Raman peak reverted to its initial value at the relax state (∼4 cm −1 , about the value for bulk Si 63 ), which further validates the elasticity of the bending process.…”

Section: Origin Of the Remarkable Thermal Conductivitymentioning

confidence: 99%

Remarkable Thermal Conductivity Reduction of Silicon Nanowires during the Bending Process

Huang,

Zhang,

Fan

et al. 2023

ACS Appl. Mater. Interfaces

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The one-dimensional geometry of silicon nanowire helps to overcome the rigid and brittle nature of bulk silicon and enables it to withstand substantial bending stresses. This provides exciting opportunities for the development of flexible electronics. The bending strain introduces atomic displacement in the lattice structure, which inherently has a significant impact on the thermal conductivity. The strain-dependent thermal conductivity of silicon nanowire is crucial to the thermal management and performance of flexible electronic devices. However, in situ thermal conductivity measurement of bending silicon nanowires remains challenging and unreported due to the varying thermal contact resistances between the sample and sensor/heat sink. In this study, the Raman spectroscopy-assisted steady state thermal conductivity measurement method is coupled with a micromanipulation system to successively monitor the thermal conductivity variation of silicon nanowires during the bending process. The result shows that the thermal conductivity of silicon nanowires steeply decreases 55−78% owing to the strain-induced structural deformation during bending. Furthermore, the proposed in situ thermal conductivity measurement method can also be extended to other nanomaterials.

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Section: Origin Of the Remarkable Thermal Conductivitymentioning

confidence: 99%

Remarkable Thermal Conductivity Reduction of Silicon Nanowires during the Bending Process

Huang,

Zhang,

Fan

et al. 2023

ACS Appl. Mater. Interfaces

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show abstract

“…By using temperature-dependent Raman scattering, we showed that these MACE NWs require 4-phonon processes to explain the Raman scattering shifts. 88,89 The thermal conductivity of the Si NWs was calculated using the same method, with the local temperature calculated using the Raman shift of the zone-center LO phonon. At a laser power of 25 mW under 532 nm excitation, the LO mode shifted to a value of 513.8 cm -1 , corresponding to a local temperature of 600 K. This gives an estimate of the thermal to be in the range 12-18 W mK -1 .…”

Section: Porous Siliconmentioning

confidence: 99%

(Invited) Material Porosity

O’Dwyer¹

2022

ECS Trans.

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Big pores, small pores, ordered pores, random pores – they all have a function and as is often found, show behaviour in new materials that is not always predicted or obvious at the outset. I started my research journey trying to put extremely thin films onto near-perfect III-V crystals to control (opto)electronic properties and when the first TEM on our campus showed remarkable pore growth and structure in InP almost 21 years ago, the electrochemical modification of the InP made more sense. In this paper, I will summarise a few aspects of research into porous materials and semiconductors, from porous InP that led to studies of other porous semiconductors such as silicon, GaN, ZnO and Indium Tin oxide (ITO), to periodically ordered photonic crystal porous structures and some optical, thermal and electrochemical properties, photocatalysis, studies in batteries and related that were enabled or modified by the porous structure.

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“…In particular, a conductivity smaller than 10 W/(m K) has been reported in 2003 by Li et al [ 21 ] for monocrystalline silicon nanowires smaller than 30 nm. Since that year, many experimental works have been devoted to the measurement of the thermal conductivity together with other thermoelectric parameters of silicon nanowires and nanostructures [ 14 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. In 2008, two famous works have been published on Nature Letters: both Hockbaum et al [ 23 ] (who used Metal Assisted Chemical Etching for the production of nanowires) and Boukay et al [ 36 ] reported the thermal conductivity of SiNWs; they positioned one, or very few, nanowires on suspended platforms, completed with microfabricated heaters and thermometers, and both of them achieved a thermal conductivity below 2 W/(m K).…”

Section: Thermoelectric Properties Of Nanostructured Siliconmentioning

confidence: 99%

Silicon Nanowires: A Breakthrough for Thermoelectric Applications

2021

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The potentialities of silicon as a starting material for electronic devices are well known and largely exploited, driving the worldwide spreading of integrated circuits. When nanostructured, silicon is also an excellent material for thermoelectric applications, and hence it could give a significant contribution in the fundamental fields of energy micro-harvesting (scavenging) and macro-harvesting. On the basis of recently published experimental works, we show that the power factor of silicon is very high in a large temperature range (from room temperature up to 900 K). Combining the high power factor with the reduced thermal conductivity of monocrystalline silicon nanowires and nanostructures, we show that the foreseen figure of merit ZT could be very high, reaching values well above 1 at temperatures around 900 K. We report the best parameters to optimize the thermoelectric properties of silicon nanostructures, in terms of doping concentration and nanowire diameter. At the end, we report some technological processes and solutions for the fabrication of macroscopic thermoelectric devices, based on large numbers of silicon nanowire/nanostructures, showing some fabricated demonstrators.

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The Nature of Silicon Nanowire Roughness and Thermal Conductivity Suppression by Phonon Scattering Mechanisms

Cited by 12 publications

References 45 publications

Remarkable Thermal Conductivity Reduction of Silicon Nanowires during the Bending Process

Remarkable Thermal Conductivity Reduction of Silicon Nanowires during the Bending Process

(Invited) Material Porosity

Silicon Nanowires: A Breakthrough for Thermoelectric Applications

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