Induced Growth of Asymmetric Nanocantilever Arrays on Polar Surfaces

We report that the Zn-terminated ZnO (0001) polar surface is chemically active and the oxygen-terminated $(000\overline{1})$ polar surface is inert in the growth of nanocantilever arrays. Longer and wider “comblike” nanocantilever arrays are grown from the (0001)-Zn surface, which is suggested to be a self-catalyzed process due to the enrichment of Zn at the growth front. The chemically inactive $(000\overline{1})\mathrm{\text{−}}\mathrm{O}$ surface typically does not initiate any growth, but controlling experimental conditions could lead to the growth of shorter and narrower nanocantilevers from the intersections between $(000\overline{1})\mathrm{\text{−}}\mathrm{O}$ with $\pm (01\overline{1}0)$ surfaces.