Optical Color Structuring via DALP-Fabricated Thin-Film Interference Cavities in ZnO/SiO2 on Si

We present a novel 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. RCWA simulations accurately predict the reflectance spectra, closely matching experimental results. Mapping the colors on the CIE 1931 diagram confirms agreement with design targets. DALP-based, lithography-free approach enables fast prototyping of spatially controlled structural color filters.