Large-area fabrication of high aspect ratio tantalum photonic crystals for high-temperature selective emitters
نویسندگان
چکیده
The authors present highly selective emitters based on two-dimensional tantalum (Ta) photonic crystals, fabricated on 2 in. polycrystalline Ta substrates, for high-temperature applications, e.g., thermophotovoltaic energy conversion. In this study, a fabrication route facilitating large-area photonic crystal fabrication with high fabrication uniformity and accuracy, based on interference lithography and reactive ion etching is discussed. A deep reactive ion etch process for Ta was developed using an SF6=C4F8 based Bosch process, which enabled us to achieve 8:5 lm deep cavities with an aspect ratio of 8, with very steep and smooth sidewalls. The thermal emitters fabricated by this method show excellent spectral selectivity, enhancement of the emissivity below cut-off approaching unity, and a sharp cut-off between the high emissivity region and the low emissivity region, while maintaining the low intrinsic emissivity of bare Ta above the cut-off wavelength. The experimental results show excellent agreement with numerical simulations. VC 2013 American Vacuum Society. [http://dx.doi.org/10.1116/1.4771901]
منابع مشابه
High-temperature stability and selective thermal emission of polycrystalline tantalum photonic crystals.
We present the results of extensive characterization of selective emitters at high temperatures, including thermal emission measurements and thermal stability testing at 1000 °C for 1h and 900 °C for up to 144 h. The selective emitters were fabricated as 2D photonic crystals (PhCs) on polycrystalline tantalum (Ta), targeting large-area applications in solid-state heat-to-electricity conversion....
متن کاملFabrication of an Omnidirectional 2D Photonic Crystal Emitter for Thermophotovoltaics
In a thermophotovoltaic (TPV) system, a heat source brings an emitter to incandescence and the spectrally confined thermal radiation is converted to electricity by a low-bandgap photovoltaic (PV) cell. Efficiency is dominated by the emitter’s ratio of in-band emissivity (convertible by the PV cell) to out-of-band emissivity (inconvertible). Two-dimensional photonic crystals (PhCs) offer high in...
متن کاملHigh-temperature tantalum tungsten alloy photonic crystals: Stability, optical properties, and fabrication
متن کامل
Global optimization of omnidirectional wavelength selective emitters/absorbers based on dielectric-filled anti-reflection coated two-dimensional metallic photonic crystals.
We report the design of dielectric-filled anti-reflection coated (ARC) two-dimensional (2D) metallic photonic crystals (MPhCs) capable of omnidirectional, polarization insensitive, wavelength selective emission/absorption. Using non-linear global optimization methods, optimized hafnium oxide (HfO2)-filled ARC 2D Tantalum (Ta) PhC designs exhibiting up to 26% improvement in emittance/absorptance...
متن کاملHigh aspect ratio LiNbO3 photonic crystals Toward 3D LiNbO3 micro and nano structures
We report easy to implement techniques for the fabrication of high aspect ratio LiNbO3 photonic crystals. The methods rely on optical grade dicing followed by focused ion beam (FIB) milling. A 2D photonic crystal with an extinction ratio of -14dB is demonstrated. We show how the techniques can be combined for the development of 3D photonic crystals. LiNbO3, ridge waveguides; photonic crystals,
متن کامل