Near-Field Radiation Calculated With an Improved Dielectric Function Model for Doped Silicon

2008 ◽  
Author(s):  
S. Basu ◽  
B. J. Lee ◽  
Z. M. Zhang
Keyword(s):  
Energy Transfer ◽  
Dielectric Function ◽  
Near Field ◽  
Silicon Surfaces ◽  
Function Model ◽  
Fluctuation Dissipation ◽  
Doped Silicon ◽  
Energy Conversion Systems ◽  
Field Radiation ◽  
Vacuum Gap

This paper describes a theoretical investigation of near-field radiative heat transfer between doped silicon surfaces separated by a vacuum gap. Using an improved dielectric function model for heavily doped silicon, along with fluctuation-dissipation theorem, and dyadic Green’s function, the present authors calculated the energy transfer between the doped silicon surfaces near room temperature. The effects of doping level, polarization, and width of the vacuum gap on the overall radiative transfer were investigated. It was observed that increase in the doping concentration of the emitter does not necessarily enhance the energy transfer in the near field. The energy-streamline method was used to model the lateral shift of the energy pathway, which is the trace of the Poynting vectors in the vacuum gap. The analysis performed in this study may facilitate the understanding of near-field radiation for applications such as thermal management in nanoelectronics, energy conversion systems, and nanothermal manufacturing.

Near-Field Radiation Calculated With an Improved Dielectric Function Model for Doped Silicon

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
S. Basu ◽  
B. J. Lee ◽  
Z. M. Zhang
Keyword(s):  
Dielectric Function ◽  
Local Density ◽  
Near Field ◽  
Silicon Surfaces ◽  
Function Model ◽  
Doped Silicon ◽  
Field Radiation ◽  
Heavily Doped ◽  
Poynting Vectors ◽  
Vacuum Gap

This paper describes a theoretical investigation of near-field radiative heat transfer between doped silicon surfaces separated by a vacuum gap. An improved dielectric function model for heavily doped silicon is employed. The effects of doping level, polarization, and vacuum gap width on the spectral and total radiative transfer are studied based on the fluctuational electrodynamics. It is observed that increasing the doping concentration does not necessarily enhance the energy transfer in the near-field. The energy streamline method is used to model the lateral shift of the energy pathway, which is the trace of the Poynting vectors in the vacuum gap. The local density of states near the emitter is calculated with and without the receiver. The results from this study can help improve the understanding of near-field radiation for applications such as thermophotovoltaic energy conversion, nanoscale thermal imaging, and nanothermal manufacturing.

Effect of Curvature on Near-Field Radiative Transfer: The Modified Proximity Approximation

2012 ◽  
Author(s):  
Karthik Sasihithlu ◽  
Arvind Narayanaswamy
Keyword(s):  
Energy Transfer ◽  
Radiative Transfer ◽  
Helmholtz Equation ◽  
Near Field ◽  
Surface Polariton ◽  
Spherical Waves ◽  
Fluctuation Dissipation ◽  
Fluctuation Dissipation Theorem ◽  
Parallel Surfaces ◽  
Proximity Approximation

Near-field radiative transfer between two spheres can be computed using Rytov’s theory of fluctuational electrodynamics in which the strength of electromagnetic sources is related to temperature through the fluctuation-dissipation theorem, and the resultant energy transfer is described using an expansion of the dyadic Green’s function of the vector Helmholtz equation in a series of vector spherical waves. We show that when electromagnetic surface waves are active at a frequency the number of vector spherical waves required for convergence is proportional to Rmax/d when d/Rmax → 0, where Rmax is the radius of the larger sphere, and d is the smallest gap between the two spheres. Using this criterion, we show that the surface polariton mediated near–field thermal radiative conductance between two spheres of equal radii R scales as R/d as d/R → 0. We also propose a modified form of the proximity approximation to predict near–field radiative transfer between curved objects from simulations of radiative transfer between parallel surfaces.

Tuning near field radiation by doped silicon

2013 ◽  
Vol 102 (18) ◽  
pp. 183114 ◽  
Author(s):  
Jiawei Shi ◽  
Pengfei Li ◽  
Baoan Liu ◽  
Sheng Shen
Keyword(s):  
Near Field ◽  
Doped Silicon ◽  
Field Radiation

Thermal transport across a pair of thin silicon films with the presence of minute vacuum gap: effect of film thickness on thermal characteristics

2016 ◽  
Vol 94 (9) ◽  
pp. 933-944 ◽  
Author(s):  
Haider Ali ◽  
Bekir Sami Yilbas
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Energy Transport ◽  
Near Field ◽  
Radiation Heat Transfer ◽  
Silicon Films ◽  
Radiation Heat ◽  
Field Radiation ◽  
Thin Silicon ◽  
Vacuum Gap

Energy transport across a pair of thin silicon films with the vacuum gap at the films interface is studied. The Boltzmann transport equation is incorporated in the analysis and the solution for the transient frequency-dependent phonon distribution across the films pair is presented. To assess the phonon characteristics, equivalent equilibrium temperature is introduced, which resembles the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Because the gap size is comparable to the mean free path of silicon, a near-field radiation heat transfer is incorporated across the film edges at the interface. The frequency cutoff method is used at the interface of the films and the phonons jump across the gap resembling the ballistic phonon contribution to the energy transport is accommodated. The thermal conductivity data predicted are validated with the data obtained from the previous study. The effect of near-field radiation heat transfer on temperature increase at the edges of the film, across the gap interface, is not considerable as compared to that corresponding to phonons transmitted across the gap. Increasing the first film thickness increases temperature difference across the gap, which is more pronounced for large gap sizes.

Near Field Surface Wave Enhanced Photon Transport

2003 ◽  
Author(s):  
Arvind Narayanaswamy ◽  
Gang Chen
Keyword(s):  
Energy Transfer ◽  
Near Field ◽  
Black Body ◽  
Black Body Radiation ◽  
Radiative Energy ◽  
Radiative Energy Transfer ◽  
Fluctuation Dissipation ◽  
Polar Materials ◽  
Photovoltaic Material ◽  
Classical Radiation

Radiative energy transfer as described by the classical radiation transfer theory of Planck is valid only when the distance between the participating surfaces is larger than a few wavelengths of the characteristic radiation. When the spacing is comparable to the wavelength, electromagnetic theory and the fluctuation-dissipation theorem can be used to predict the energy transfer between the surfaces. We have used the electromagnetic Green’s function method to model the thermal energy transfer between two half planes with planar layers in between. With polar materials as the half planes, we see a narrowband energy transfer in the near field due to energy transfer by surface phonon polaritons. We have used this technique to show that such a resonance, however dampened, persists even with the presence of a layer of photovoltaic material. This results in not only an increased energy transfer to the photovoltaic material as compared to black body radiation but also imparts a narrowband characteristic to it. The implications for thermophotovoltaics are discussed.

Microscale Thermal Energy Transfer Between Thin Films with Vacuum Gap at Interface

2019 ◽  
Vol 44 (2) ◽  
pp. 123-142 ◽  
Author(s):  
Haider Ali ◽  
Bekir Sami Yilbas
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Transfer ◽  
Radiative Heat ◽  
Near Field ◽  
Silicon Film ◽  
Phonon Transport ◽  
Ballistic Phonons ◽  
Vacuum Gap

Abstract Transfer of phonons through a silicon–diamond thin film pair with a nano-size gap at the interface is examined. The thin film pair is thermally disturbed by introducing 301 K at the silicon film left edge while keeping the other edges of the thin films at a low temperature (300 K). The radiative phonon transport equation is solved numerically to quantify the phonon intensity distribution in the combined films. The frequency dependent formulation of phonon transport is incorporated in the transient analysis. The thermal boundary resistance is adopted at the interface in the formulations. The near-field radiative heat transfer is also adopted at the gap interface, as the vacuum gap size falls within the Casimir limit. The predictions of thermal conductivity are validated through the thermocouple data. It is observed that predictions of thermal conductivity are in agreement with the experimental data. The ballistic phonons play a major role in energy transfer through the gap; their contribution is more significant than that of the near-field radiative heat transfer. Enlarging the size of the gap reduces the influence of the ballistic phonons on the energy transfer in the films. Increasing the silicon film thickness alters the energy transfer through the gap; in this case, the equivalent equilibrium temperature difference is increased at the interface.

Tuning Near Field Radiation by Doped Silicon

2013 ◽  
Author(s):  
Jiawei Shi ◽  
Sheng Shen
Keyword(s):  
Silicon Dioxide ◽  
Theoretical Calculation ◽  
Carrier Concentration ◽  
Tuning Range ◽  
Near Field ◽  
Bulk Silicon ◽  
Doped Silicon ◽  
Theoretical Predictions ◽  
Field Radiation ◽  
Radiation Measurements

In this letter, we demonstrate theoretically and experimentally that bulk silicon can be employed to overcome the challenge of tuning near field radiation. Theoretical calculation shows that the nanoscale radiation between bulk silicon and silicon dioxide can be tuned by changing the carrier concentration of silicon. Near field radiation measurements are carried out on multiple bulk silicon samples with different doping concentrations. The measured near field conductance agrees well with theoretical predictions, which demonstrates a tuning range from 2 nW/K to 6 nW/K at a gap of ∼60 nm.

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