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Proceedings Paper

Large area selective emitters/absorbers based on 2D tantalum photonic crystals for high-temperature energy applications
Author(s): V. Rinnerbauer; Y. X. Yeng; J. J. Senkevich; J. D. Joannopoulos; M. Soljačić; I. Celanovic
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Paper Abstract

We report highly selective emitters based on high-aspect ratio 2D photonic crystals (PhCs) fabricated on large area (2 inch diameter) polycrystalline tantalum substrates, suitable for high-temperature operation. As an example we present an optimized design for a selective emitter with a cut-off wavelength of 2μm, matched to the bandgap of an InGaAs PV cell, achieving a predicted spectral selectivity of 56.6% at 1200K. We present a fabrication route for these tantalum PhCs, based on standard microfabrication processes including deep reactive ion etch of tantalum by an SF6 based Bosch process, achieving high-aspect ratio cavities (< 8:1). Interference lithography was used to facilitate large area fabrication, maintaining both fabrication precision and uniformity, with a cavity diameter variation of less than 2% across the substrate. The fabricated tantalum PhCs exhibit strong enhancement of the emittance at wavelengths below cut-off wavelength, approaching that of blackbody, and a steep cut-off between high and low emittance spectral regions. Moreover, detailed simulations and numerical modeling show excellent agreement with experimental results. In addition, we propose a surface protective coating, which acts as a thermal barrier coating and diffusion inhibitor, and its conformal fabrication by atomic layer deposition.

Paper Details

Date Published: 21 February 2013
PDF: 8 pages
Proc. SPIE 8632, Photonic and Phononic Properties of Engineered Nanostructures III, 863207 (21 February 2013); doi: 10.1117/12.2005202
Show Author Affiliations
V. Rinnerbauer, Massachusetts Institute of Technology (United States)
Y. X. Yeng, Massachusetts Institute of Technology (United States)
J. J. Senkevich, Massachusetts Institute of Technology (United States)
J. D. Joannopoulos, Massachusetts Institute of Technology (United States)
M. Soljačić, Massachusetts Institute of Technology (United States)
I. Celanovic, Massachusetts Institute of Technology (United States)


Published in SPIE Proceedings Vol. 8632:
Photonic and Phononic Properties of Engineered Nanostructures III
Ali Adibi; Shawn-Yu Lin; Axel Scherer, Editor(s)

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