Optical color structuring via DALP-fabricated thin-film interference cavities in ZnO/SiO₂ on Si

We present a method for generating structural colors using direct atomic layer processing (DALP) to fabricate thin-film interference cavities made of ZnO and SiO₂ on silicon. By locally depositing successive layers and thus varying ZnO thickness from a few nanometers up to 150 nm, we achieve tunable reflective colors via depth modulation. The asymmetric interference cavities produce vivid hues through optical interference. Rigorous coupled-wave analysis simulations accurately predict the reflectance spectra, closely matching experimental results. Mapping the colors on the CIE 1931 diagram confirms agreement with design targets. A DALP-based, lithography-free approach enables fast prototyping of spatially controlled structural color filters.