Growth of Vertical ZnO Nanorods from Patterned Films via Decomposition of Zinc Acetate by Focused Ion Beam: Implication for UV Detection

Zinc oxide (ZnO) nanorod arrays have a wide range of applications. Controlling the position of the seed layers (ZnO films) and the nanorod morphology plays an essential role in the fabrication of the sensors and the fulfilment of specific sensing properties, while the patterning of seed layers and controlling the NR morphology have mostly been studied separately. In this study, a focused ion beam was employed to decompose spin-coated zinc acetate films for the precise positioning of the seed layers. The resulting ZnO films were used to hydrothermally grow vertical ZnO NRs that process a high responsivity of 1.24 × 106 A/W at a bias voltage of 5 V. Moreover, this approach provides the following advantages: (1) the carbon to zinc ratio of the zinc acetate film decreased from 4:1 to 1:18.9 after irradiation, demonstrating the efficient decomposition; (2) a patterned ZnO film can be obtained with a low irradiation dose of 1000 μC/cm2; and (3) the seed layer can be utilized directly for vertical nanorod growth without annealing. The morphology of NRs is characterized, and the nanorods grown on seed layers under different treatment conditions had different X-ray diffraction (XRD) peak patterns. Furthermore, the UV–vis absorption spectra of the nanorods were measured. Finally, we examined the rapid patterning of the ZnO thin films. We propose a simple and efficient approach for the decomposition of zinc acetate into patterned ZnO; this provides an integrated solution for ZnO film positioning and the vertical growth of ZnO NRs, which could also offer an approach and inspiration for ultraviolet (UV) detection and ideas for the localized growth of other ZnO nanomaterials.