Fabrication of ZnO microstructures by anisotropic wet-chemical etching

ZnO microstructures were fabricated by wet-chemical etching with aqueous solutions of HCl and CH3COOH and patterned resist masks prepared by electron-beam lithography. Anisotropy of the etching rate caused the formation of microstructures corresponding to the crystal habit. In fact, all the pit structures made on (0001), (1010), and (1120) surfaces of ZnO single crystal were characterized by {101n} (n = integer) faces, and all the pyramidal structures made on the (0001) surface were characterized by {112n} facets forming hexagonal projections. Regarding etchant dependence, CH3COOH[aq] enabled us to create structures with sharp edges and corners, while etching with HCl[aq] resulted in structures with rounded shapes. The coalescence of pits during chemical etching was also investigated using mask patterns having symmetrically aligned windows that were close to each other. (c) 2006 The Electrochemical Society.