Low-weight, passive, thermal-adaptive radiation technologies are needed to maintain an operable temperature for spacecraft while they experience various energy fluxes. Vanadium dioxide (VO2) is a commonly used dynamic response material that can transition from a low emissivity (insulating) state to a high emissivity (radiating) state near room temperature. In this study, we used a thin-film coating with the Fabry-Perot (FP) effect to enhance emissivity contrast (Δε) between the VO2 phase-change states. This coating utilizes a novel hybrid material architecture that combines VO2 with the mid- and long-wave infrared transparent chalcogenide, zinc sulfide (ZnS) as a cavity spacer layer. We simulated the design parameter space to obtain a theoretical maximum Δε of 0.63 and grew a prototype device. Using x-ray diffraction, Raman spectroscopy, and Fourier Transform Infrared (FTIR) Spectroscopy, we determined that an intermediate buffer layer of TiO2 is necessary to execute the polycrystalline growth of VO2 on ZnS. We optically characterized the pulsed laser deposition grown VO2 and ZnS using IR-spectroscopic ellipsometry. Through measuring the temperature-dependent FTIR spectroscopy, our prototype sample demonstrated FP-cavity enhanced adaptive thermal emittance.
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