Research and fabrication of color filters based on porous anodic alumina

Abstract

This study introduces a porous alumina composite structure, incorporating silver on a silicon substrate, to achieve a wide range of color displays. The structure utilizes the Bragg interference effect to reflect light between the surface and the pore bottoms. Fabrication involved magnetron sputtering, anodizing, and sodium hydroxide etching to produce different pore sizes, depths, and silver film thicknesses. This method shifts reflection valleys in the spectrum, enabling light emission or absorption across various wavelengths, resulting in diverse color displays. Experiments reveal that hue is influenced by pore depth, pore size, and silver film thickness, whereas brightness and saturation are regulated by pore size and silver film thickness. Unlike periodic structural color filters made through complex methods like photolithography and self-assembly, this filter is easily manufactured using simple electrochemical and coating techniques. This cost-effective, simple, and controllable method is ideal for large-scale production and the creation of high-resolution, high-saturation structural color display devices.