Heteroepitaxial Si/ZnO hierarchical nanostructures for future optoelectronic devices.

The synthesis of highly-ordered ultra-dense heteroepitaxial Si/ZnO hierarchical nanostructures by a simple and cost-effective approach is demonstrated. We also show, based on the same approach, the synthesis of ZnO nanoparticle-decorated Si nanowire cores and Si/ZnO conformal core-shell hetero-nanostructures. The as-synthesized ZnO nanobranches on Si nanowire cores exhibit an epitaxial relationship as (111)Si/(100) ZnO. Excellent control over the composition, dimensions, and density of ZnO branches on Si cores has been achieved. Thus, in future, this family of well-controlled, high-quality Si/ZnO hierarchical hetero-nanostructures could play a role as multifunctional candidates in the fabrication of optoelectronic devices, particularly for the development of a new generation of solar-cell devices.