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

The fabrication of nano-/microsized columns and hole arrays oil an n-GaAs substrate was carried out using a combination of colloidal crystal templating, electrohess plating/two-step catalyzation, and subsequent metal-assisted chemical etching. Using self-assembled polystyrene spheres as a mask, metal particles, specifically Ag and Pd, were selectively deposited at the interspaces between the polystyrene spheres, resulting in the formation of metal honeycomb patterns oil GaAs. Ordered GaAs column arrays were then fabricated by the chemical etching of the GaAs originating from the honeycomb-patterned Ag and Pd metals, which acted is etching catalysts. Each metal catalyst resulted in the formation of a characteristic etched structure and etching depth. Pd-etched column arrays exhibited conical Structures, while Ag-etched specimens showed slender column structures owing to the anisotropic etching of the GaAs. Moreover, patterned-GaAs slender grooves exhibiting triangular cross sections were fabricated by Ag-assisted chemical etching. To obtain the groove structures, honeycomb-structural polystyrene spheres were used as in etching mask. After the chemical etching of the GaAs, patterned slender grooves were formed. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3197239] All rights reserved.