ZnO/Cu₂O heterostructure nanopillar arrays: synthesis, structural and optical properties

Vertically aligned ZnO/Cu 2 O heterostructure nanopillar arrays consisting of a ZnO core and a Cu 2 O shell were fabricated by a two-step electrochemical deposition method. Morphological, structural and optical properties of the nanopillar heterojunctions were investigated. The surface of the single-crystalline ZnO nanopillars was coated uniformly, conformally and densely over the entire nanopillar length by numerous Cu 2 O nanocrystals (25–35 nm mean diameter), constituting a conformal shell layer 90 nm thick, integrating these two materials into an electronically intimate composite. The optical properties can be interpreted, by appropriate fittings of each feature, as being due to the properties of the bare ZnO nanopillar array plus the increased absorption of Cu 2 O. This study demonstrates that electrodeposition is a suitable and accessible technique for large-scale fabrication of nanopillar heterostructures and to achieve conformal coverage of nanostructured samples.