  Low-weight, passive, thermal-adaptive radiation technologies are needed to
maintain an operable temperature for spacecraft while they experience various
energy fluxes. In this study, we used a thin-film coating with the Fabry-Perot
(FP) effect to enhance emissivity contrast ({\Delta}{\epsilon}) between VO2
phase-change states. This coating utilizes a novel hybrid material architecture
that combines VO2 with a 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 {\Delta}{\epsilon} of 0.63 and grew
prototype devices. 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 crystalline growth of
monoclinic VO2 on ZnS. Through temperature-dependent FTIR spectroscopy
measurements, our fabricated devices demonstrated FP-cavity enhanced adaptive
thermal emittance.
