Effects of Substrate Temperature and RF Power on the Formation of Aligned Nanorods in ZnO Thin Films

We report on the effects of substrate temperature and RF power on the formation of aligned nanorod-like morphology in ZnO thin films. ZnO thin films were sputter-deposited in mixed Ar and N₂ gas ambient at various substrate temperatures and RF powers. We find that the substrate temperature plays more important role than RF power in the formation of ZnO nanorod-like morphology. At low substrate temperatures (below 300°nO nanorod-like morphology does not form regardless of RF powers. High RF power helps to promote the formation of aligned ZnO nanorod-like morphology. However, lower RF powers usually lead to ZnO films with better crystallinity at the same substrate temperatures in mixed Ar and N₂ gas ambient and therefore better photoelectrochemical response.