Enhancement of zinc interstitials in ZnO nanotubes grown on glass substrate by the hydrothermal method

In this study, high density well aligned ZnO nanotubes were grown on glass via a two-step growth-then-etching by simple and template-free hydrothermal method. We used etching procedure to introduce additional zinc interstitial defects in the ZnO nanotubes. The optical properties of the ZnO nanotubes have been investigated by depth-resolved cathodluminescence spectroscopy (DRCLS) which provides information about the physical origin and growth dependence of optically active defects together with their spatial distribution. The DRCLS study gives clear evidence about the enhancement of zinc interstitial defects which are responsible for the violet and decrease of the DL emission in ZnO nanotubes when compared to the as grown ZnO nanorods. We observed a variation in the zinc interstitials along the nanotube depth.