Thermal radiation from silicon microcavity coated with thermochromic film

A high thermochromic performance is required for the thermochromic film application in space radiator. The performance can be improved by material selection or structure design. Here, we constructed a two-dimensional structure composed of silicon microcavity array coated with thermochromic film. From detailed numerical simulation, we found that periodic microcavity array plays a key role in enhancing the spectral emittance. For 1.5 μm deep microcavity with a 500 nm thick thermochromic film, an emittance peak appears at the wavelength of 12.7 μm, which corresponds to the Fabry-Perot (FP) resonance mode. Another microcavity excitation was observed in the shorter wavelength region, which matches well with its resonance wavelength. Based on the simulations, the optimal structure was fabricated by etching and sputtering methods. The fabricated structure shows a high tunable emittance behavior with emittance increment reaching 0.41. Both the experiment and simulation identified that the microcavity beneath thermochromic film can improve its thermochromic performance.