Tuning thermal conductivity of nanoporous crystalline silicon by surface passivation: A molecular dynamics study

Fang, Jin; Pilon, Laurent

doi:10.1063/1.4733352

Cited by 17 publications

(12 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given the large surface‐to‐volume ratio, the morphology at the pore surface can also change the nature of scattering and hence the thermal conductivity. In order to minimize the surface energy, the free bonds at the pore surface are usually passivated by oxygen or hydrogen . This passivation of atoms leads to further energy exchange between the silicon atoms by changing their vibrational spectra .…”

Section: Introductionmentioning

confidence: 99%

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Zhao

Yang

Kong

et al. 2017

Adv Funct Materials

View full text Add to dashboard Cite

Porous materials provide a large surface-to-volume ratio, thereby providing a knob to alter fundamental properties in unprecedented ways. In thermal transport, porous nanomaterials can reduce thermal conductivity by not only enhancing phonon scattering from the boundaries of the pores and therefore decreasing the phonon mean free path, but also by reducing the phonon group velocity. Herein, a structure-property relationship is established by measuring the porosity and thermal conductivity of individual electrolessly etched single-crystalline silicon nanowires using a novel electron-beam heating technique. Such porous silicon nanowires exhibit extremely low diffusive thermal conductivity (as low as 0.33 W m −1 K −1 at 300 K for 43% porosity), even lower than that of amorphous silicon. The origin of such ultralow thermal conductivity is understood as a reduction in the phonon group velocity, experimentally verified by measuring the Young's modulus, as well as the smallest structural size ever reported in crystalline silicon (<5 nm). Molecular dynamics simulations support the observation of a drastic reduction in thermal conductivity of silicon nanowires as a function of porosity. Such porous materials provide an intriguing platform to tune phonon transport, which can be useful in the design of functional materials toward electronics and nanoelectromechanical systems.

show abstract

Section: Introductionmentioning

confidence: 99%

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Zhao

Yang

Kong

et al. 2017

Adv Funct Materials

View full text Add to dashboard Cite

show abstract

“…Finally, a similar effect of surface groups on specific and volumetric heat capacities should be considered in other mesoporous materials with a large surface area. 27,28 See supplementary material for the nomenclature and the details on the measurements of total pore volume, porosity, micropore volume, specific surface area, average pore width, specific heat, water weight fraction, FTIR transmission spectra, and XRD patterns.…”

mentioning

confidence: 99%

Effect of surface hydroxyl groups on heat capacity of mesoporous silica

Marszewski

Butts

Lan

et al. 2018

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

This paper quantifies the effect of surface hydroxyl groups on the effective specific and volumetric heat capacities of mesoporous silica. To achieve a wide range of structural diversity, mesoporous silica samples were synthesized by various methods, including (i) polymer-templated nanoparticlebased powders, (ii) polymer-templated sol-gel powders, and (iii) ambigel silica samples dried by solvent exchange at room temperature. Their effective specific heat capacity, specific surface area, and porosity were measured using differential scanning calorimetry and low-temperature nitrogen adsorption-desorption measurements. The experimentally measured specific heat capacity was larger than the conventional weight-fraction-weighted specific heat capacity of the air and silica constituents. The difference was attributed to the presence of OH groups in the large internal surface area. A thermodynamic model was developed based on surface energy considerations to account for the effect of surface OH groups on the specific and volumetric heat capacity. The model predictions fell within the experimental uncertainty. Published by AIP Publishing. https://doi.

show abstract

“…The experimental results on pSi show that its thermal conductivity is strongly related to the pore size at a given total porosity [37][38][39]110]. Since an increasing porosity may deteriorate the electron transport properties [5,75], it would be advantageous if its effective thermal conductivity could be controlled by the volume fractions, as well as the characteristic size of the pores.…”

Section: Pore-size Dependence Of the Effective Thermal Conductivity Imentioning

confidence: 96%

“…In view of the dynamical form of the bulk heat-flow contribution (38), in the same way let us suppose that the wall contribution is given by…”

Section: Frequency Dependence Of the Effective Thermal Conductivitymentioning

confidence: 99%

Mesoscopic description of boundary effects in nanoscale heat transport

Álvarez¹,

Cimmelli²,

Jou³

et al. 2012

Nanoscale Systems: Mathematical Modeling, Theory and Applications

View full text Add to dashboard Cite

We review some of the most important phenomena due to the phonon-wall collisions in nonlocal heat transport in nanosystems, and show how they may be described through certain slip boundary conditions in phonon hydrodynamics. Heat conduction in nanowires of different cross sections and in thin layers is analyzed, and the dependence of the thermal conductivity on the geometry, as well as on the roughness is pointed out. We also analyze the effects of the roughness of the surface of the pores on the thermal conductivity of porous silicon. Thermoelectric effects are considered as well

show abstract

Tuning thermal conductivity of nanoporous crystalline silicon by surface passivation: A molecular dynamics study

Cited by 17 publications

References 37 publications

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Ultralow Thermal Conductivity of Single‐Crystalline Porous Silicon Nanowires

Effect of surface hydroxyl groups on heat capacity of mesoporous silica

Mesoscopic description of boundary effects in nanoscale heat transport

Contact Info

Product

Resources

About