Optical Properties of Nanohole Arrays with Various Depths

Studies to imitate structural colors have been conducted with various methods, most of which are disadvantageous for mechanical stability and economic feasibility because of complexity or lack of reproducibility. Numerous alternatives to overcome these shortcomings have been proposed. One such method is the anodic oxidation of aluminum, which requires relatively simple equipment and techniques. The present study used the aluminum anodic oxidation process to fabricate nanohole arrays of various sizes. Furthermore, using the finding that the structure color is the most strongly influenced by the nanohole depth based on the Bragg`s Law, this study fabricated nanoholes of various depths to identify the structural colors arising from varied depths. This study further identified the colors from the same color series occurring periodically at each interval of 250 nm using the CIE 1931 color coordinate system. Moreover, nanohole arrays with two different depths were fabricated on a single substrate to confirm the coexistence of different colors and their capacity for deformation into various shapes.