Template-Assisted Large-Scale Ordered Arrays of ZnO Pillars for Optical and Piezoelectric Applications



Spatially separated ZnO pillars, typically 300 nm in diameter and 2 μm in height, are fabricated via a template-directed approach that leads to long-range hexagonal order. The templates of Au nanodisk arrays are obtained by using metal membranes as a lithography mask. The growth of ZnO pillars is performed in a double-tube system through vapor diffusion–deposition. The growth mechanism of the pillars is studied in detail and is proposed to be a combination of vapor–liquid–solid and vapor–solid models. The piezoelectric and optical properties of single pillars are characterized using piezoresponse force microscopy and micro-photoluminescence spectroscopy, respectively. The pillars show strong excitonic emissions up to room temperature, which indicate a relatively low defect density and good crystalline quality. The obtained piezoelectric coefficient d33 is (7.5±0.6) pm V−1, which is to our knowledge the first reported value for a single nanopillar.