Growth of ZnO nanostructures by wet oxidation of Zn thin film deposited on heat-resistant flexible substrates at low temperature

Coral-like ZnO nanostructures were successfully grown onto heat-resistant flexible substrates by the oxidation of Zn thin films. At a relatively low temperature (100$^\circ$C), Zn thin film was oxidized using a horizontal furnace under the flow of water vapour. The obtained results revealed well-defined aggregates of ZnO nanostructures grown on the flexible films. XRD patterns exhibited a strong and sharp diffraction along the (002) plane suggesting a well-crystallized ZnO phase. Field emission scanning electron microscopy observations showed high-density ZnO nanostructures aggregated in coral-like shape. The present study introduced a cost-effective and simple approach to grow high-quality ZnO nanostructures with controlled shape and size, offering a promising candidate for nano-based devices such as fast-response photodiodes and gas sensors.