Effect of surface wettability controlled by ultraviolet-ozone treatment on spin-coated ZnO seed layer and ZnO nanowires grown by hydrothermal method

We presented improved density and aspect ratio of ZnO nanowires which were hydrothermally grown on spin coated ZnO seed layer. After UVO treatment on silicon surface, spin coated ZnO seed layer showed a high coverage density due to increased surface wettability without forming island like growth in conventional method. ZnO active nucleation sites showed a positive increasing relation with increase in coverage density. Whereas, increased spin coating time had risen surface roughness with rise in coverage area, UVO treated surface wettability change had showed lower surface roughness. Moreover, seed layer thickness remained unaffected for surface wettability changing effect. This let ZnO nanowires grow on the increased ZnO active nucleation sites without hindrance of other nanowires. Hence, higher density and aspect ratio ZnO nanowires were achieved by controlling surface wettability via UVO treatment.