Mie-Resonant Structural Color of Silicon Nanosphere Monolayer Coupled with Fabry–Pérot Cavity

Silicon (Si) nanospheres (NSs), 100–200 nm in diameter, exhibit size-dependent scattering colors due to the Mie resonances. Because of the very high scattering efficiency, reflectance of ∼50% can be achieved in the monolayers, and thus ultrathin and lightweight color painting is possible with the Si NSs. In this work, we explore the possibility of controlling the color of Si NS monolayers by coupling them with a Fabry–Pérot cavity for potential applications in dynamic color displays and environment sensors. First, scattering spectra of a single Si NS placed on a Si mirror via a silicon dioxide (SiO2) spacer are studied by numerical simulations for different spacer thicknesses. Similar simulations are then made for Si NS monolayers. The numerical results reveal that the reflected color can be tuned through the coupling strength of the spacer acting as a Fabry–Perot cavity and Mie resonances of Si NSs. Following the numerical results, Si NS monolayers are produced from the colloidal suspensions by the Langmuir–Blodgett method on surface-oxidized Si wafers, and color control is experimentally demonstrated.