Controlled etching of hexagonal ZnO architectures in an alcohol thermal process

An alcohol thermal technique was applied to the controlled growth of hexagonal ZnO architectures via selective chemical etching. ZnO microdisks were produced first under mild alcohol thermal conditions in presence of formamide. Due to a higher surface energy/atomic density of Zn{sup 2+} {l_brace}0 0 0 1{r_brace} than that of the other faces, hexagonal ZnO microring was obtained by selectively etching positive polar surface of disk-like precursor with a high density of planar defects at the center. The selective etching of ZnO is related to its crystallographic characteristics of surface polarity and chemical activities, which opens a new opportunity for the shape-controlled synthesis of wurtzite-structured materials.