Size and surface orientation effects on thermal expansion coefficient of one-dimensional silicon nanostructures

Zhao, Hong Jian; Aluru, N. R.

doi:10.1063/1.3126499

Cited by 14 publications

(10 citation statements)

References 17 publications

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“…In fact, the Tersoff potential used in this study was employed to investigate surface reconstruction of Si. 81,82 Accordingly, we prepared Si/n-graphene/Si samples with (111) reconstructed surfaces.…”

Section: Effect Of Surface Reconstruction Crystallographic Orientmentioning

confidence: 99%

Heat transfer mechanism across few-layer graphene by molecular dynamics

2013

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We use nonequilibrium molecular dynamics to study heat transfer across structures consisting of a few layers of graphene sandwiched between silicon crystals. We find that when heat transfers from a silicon lead on one side across the graphene layers to a silicon lead on the other side, the interfacial conductance is essentially independent of the number of layers, in agreement with recent experimental findings. By contrast, wave-packet simulations show that the transmission coefficient of individual vibrational modes depends strongly on frequency and the number of graphene layers, indicating significant interference effects. This apparent contradiction is resolved by a theoretical calculation, which shows that the integrated contribution of the phonons to the interfacial thermal conductance is essentially independent of the number of layers. When one atomic layer of graphene is heated directly, the effective interfacial conductance associated with heat dissipation to the silicon substrate is much smaller. We attribute this to the resistance associated with heat transfer between high and low frequency modes within heated graphene.

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Section: Effect Of Surface Reconstruction Crystallographic Orientmentioning

confidence: 99%

Heat transfer mechanism across few-layer graphene by molecular dynamics

2013

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“…2(e)) at room temperature. 28,29 Often, these dangling bonds are terminated with hydrogen atoms to avoid surface reconstruction and other forms of surface defects. We first look into the case of hydrogen (H) terminated silicon surface.…”

Section: Resultsmentioning

confidence: 99%

Mixed role of surface on intrinsic losses in silicon nanostructures

Kunal

Aluru

2016

Journal of Applied Physics

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We utilize molecular dynamics simulations and show opposing roles of surface on dissipation in nanostructures. While the surface defects always aid in the entropy generation process, the scattering of phonons from rough surfaces can suppress Akhiezer damping. For the case of a silicon (2 Â 1) reconstructed surface, the former dominates and Q À1 (Q is the quality factor) is found to increase with the decrease in size. However, different scaling trends are observed in the case of a hydrogen (H) terminated silicon surface with no defects and dimers. Particularly, in the case of a H-terminated silicon, if the resonator is operated with a frequency X such that Xs ph < 1, where s ph is the phonon relaxation time and Q À1 is found to decrease with the decrease in size. The opposite scaling is observed for Xs ph > 1. A simplified model, based on two phonon groups (with positive and negative Gr€ uneisen parameters), is considered to explain the observed trend. We show that the equilibration time between the two mode groups decreases with the decrease in size for the H-terminated structure. We also study the scaling of Q À1 factor with frequency for these cases.

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“…The variation in dimensions are calculated using the thermal expansion coefficients for silicon: α [110] and α [100] , corresponding to the length and thickness of the layer respectively, taken from [14]. The new dimension at a temperature T in…”

Section: ) Thermal Expansionmentioning

confidence: 99%

“…T + 120 (13) 8) Heat capacity at constant pressure C p : The silicon molar heat capacity at constant pressure is linked to the temperature in Kelvin T k by equation (14). Expressing temperature in Celsius units and dividing by the silicon molar mass leads to the expression of C p as a function of temperature given in (16).…”

Section: ) Thermal Expansionmentioning

confidence: 99%

Experimental and Theoretical Study of a Piezoelectric Vibration Energy Harvester Under High Temperature

Arroyo

Jia

et al. 2017

J. Microelectromech. Syst.

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Abstract-This work focuses on studying the effect of increasing the ambient temperature up to 160• C on the power harvested by a MEMS piezoelectric micro-cantilever manufactured using an aluminum nitride-on-silicon fabrication process. An experimental study shows that the peak output power decreases by 60% to 70% depending on the input acceleration. A theoretical study establishes the relationship of all important parameters with temperature and includes them into a temperature-dependant model. This model shows that around 50% of the power drop can be explained by a decreasing quality factor, and that thermal stresses account for around 30% of this decrease.

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Size and surface orientation effects on thermal expansion coefficient of one-dimensional silicon nanostructures

Cited by 14 publications

References 17 publications

Heat transfer mechanism across few-layer graphene by molecular dynamics

Heat transfer mechanism across few-layer graphene by molecular dynamics

Mixed role of surface on intrinsic losses in silicon nanostructures

Experimental and Theoretical Study of a Piezoelectric Vibration Energy Harvester Under High Temperature

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