Materials Science

Core Issues in Oxide Growth

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Science  04 Oct 2002:
Vol. 298, Issue 5591, pp. 15
DOI: 10.1126/science.298.5591.15b

When metal oxides are grown from vapor onto a substrate, the exposed crystal face and the lattice mismatch of the substrate can influence the shape of the objects that form. An extreme case is presented by Lao et al., who observed a hierarchical formation of ZnO nanorods on In2O3 cores during a vapor condensation process in which single-crystal nanorods grew with six-, four-, or twofold symmetry. On smaller In2O3 cores, rows of single rods were obtained, but on larger cores, multiple rods originated from a single substrate facet. The ZnO rods typically grew perpendicularly to the core, but some variation was observed in the tilt angle. Detailed examination of the structures showed that the symmetry of the ZnO wires depended on the crystallographic orientation of the In2O3. When In2O3 was oriented along the [110] or [111] directions, sixfold symmetry was obtained, but when the In2O3 was oriented along the [001] direction, fourfold symmetry was seen. The authors believe that the twofold symmetry is controlled by yet another growth mechanism. — MSL

Nano Lett. 10.1021/nl025753t (2002).

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