Microstructural Evolution of ZnO by Wet-Etching Using Acidic Solutions
Authors: Lee, Ji-Myon; Kim, Kyoung-Kook; Hyun, Chan-Kyung; Tampo, Hitoshi; Niki, Shigeru
Source: Journal of Nanoscience and Nanotechnology, Volume 6, Number 11, November 2006 , pp. 3364-3368(5)
Publisher: American Scientific Publishers
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Abstract:
The characteristics of the wet-etching of ZnO thin films were investigated using hydrochloric and phosphoric acid solutions as etchants. The etch rate of ZnO films, using a highly diluted hydrochloric acid solutions at a concentration of 0.25% in deionized water, was determined to be about 120 nm/min, and linearly increased with increasing the acid concentration. The surface of ZnO(0001) etched by an HCl solution, observed by scanning electron microscopy, showed a rough morphology with a high density of hexagonal pyramids or cones with sidewall angles of about ∼45°. Moreover, the sidewall angles of the masked area were similar to those of the pyramids on the surface. In comparison, the surface of ZnO(0001) etched by a phosphoric acid had a smooth surface morphology. The origin of this difference is from the very initial stage of etching, indicating that the etch-mechanism is different for each solution. Furthermore, when H3PO4 was added to the HCl aqueous solution, the morphology of the etched surface was greatly enhanced and the sidewall angle was also increased to about 65°.Keywords: ETCH; MICROSTRUCTURE; SURFACE ROUGHNESS; HEXAGONAL PYRAMID; ZNO
Document Type: Research article
DOI: 10.1166/jnn.2006.011
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