Periodic GaAs Convex and Hole Arrays Produced by Metal-Assisted Chemical Etching

Periodically ordered GaAs convex and hole arrays were fabricated through a combination of colloidal crystal templating and metal-assisted chemical etching using an ion-sputtered Pt–Pd catalyst. A change in the hydrofluoric acid concentration in the etchant results in different morphologies of hole arrays, such as circular and hexagonal holes. Pt–Pd-assisted chemical etching realizes an etching structure having an aspect ratio that is better than those realized by Ag-, Pd-, and Au-assisted chemical etching. GaAs undergoing Pt–Pd-assisted chemical etching exhibited anisotropy of the etching rates with respect to the two-dimensional crystallography of the substrate.