Site-Selective Metal Patterning/Metal-Assisted Chemical Etching on GaAs Substrate through Colloidal Crystal Templating

Abstract

Systematic research on an n-GaAs substrate through a combination of colloidal crystal templating, electroless plating/two-step catalyzation and subsequent metal-assisted chemical etching was carried out. Using self-organized polystyrene spheres as a mask, metal particles, i.e., Cu, Ag and Pd, were selectively deposited at sites resulting in the formation of metal honeycomb patterns on GaAs. Ordered GaAs convex arrays were fabricated by the chemical etching of GaAs originating from the honeycomb-patterned Ag and Pd metals, which acted as etching catalysts, whereas the effectiveness of Cu as a catalyst in metal-assisted etching was not confirmed. Each metal catalyst resulted in the formation of a characteristic etched structure and etching depth, and thus, etching rate. In addition, different anisotropic etching structures were obtained by Ag-assisted etching for (100)- and (111)-oriented substrates. The crystal-face orientation as well as the metal used affects the rate of metal-assisted chemical etching and the morphology obtained.