Abstract
We demonstrate a selectively emitting optical Fabry-P\'erot resonator based on a few-nm-thin continuous metallic titanium nitride film, separated by a dielectric spacer from an optically thick titanium nitride back-reflector, which exhibits excellent stability at 1070 K against chemical degradation, thin-film instabilities and melting point depression. The structure paves the way to the design and fabrication of refractory thermal emitters using the well-established processes known from the field of multilayer and rugate optical filters. We demonstrate that a few-nanometer thick films of titanium nitride can be stable under operation at temperatures exceeding 1070 K. This type of selective emitter provides a means towards near-infrared thermal emission that could potentially be tailored to the accuracy level known from rugate optical filters.
Highlights
Accurate control of radiative heat transfer within systems and in exchange with their surroundings is of critical importance to both efficiency and feasibility of a wide variety of systems, with notable examples being energy production schemes such as solar-thermal [1, 2], thermophotovoltaic (TPV) conversion [3, 4], and - in mimicking the Saharan silver ants [5] - passive radiative daytime cooling in direct sunlight [6, 7]
We demonstrate a selectively emitting optical Fabry-Pérot resonator based on a few-nm-thin continuous metallic titanium nitride film, separated by a dielectric spacer, which exhibits excellent stability at 1070 K against chemical degradation, thin-film instabilities and melting point depression
We have previously demonstrated that a simple continuous-layer Fabry-Pérot resonator, with a dielectric layer sandwiched between two gold mirrors, can act as a thermal emitter with a tunable emission maximum placed at 1.7 μm, corresponding to the band-gap energy of GaSb [42]
Summary
Accurate control of radiative heat transfer within systems and in exchange with their surroundings is of critical importance to both efficiency and feasibility of a wide variety of systems, with notable examples being energy production schemes such as solar-thermal [1, 2], thermophotovoltaic (TPV) conversion [3, 4], and - in mimicking the Saharan silver ants [5] - passive radiative daytime cooling in direct sunlight [6, 7]. While certain bulk materials, such as some rare earth oxides [10], exhibit naturally occurring narrow-band emission near common PV band-gap energies, as well as excellent thermal stability, they are far from being ideal narrow-band emitters due to significant o ut-of-band e mission [11,12,13,14]. To simultaneously suit the spectral and other application-specific requirements, there is a strong motivation to develop emitters which enable emissivity control beyond naturally occurring bulk properties
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