Vertically arrayed ZnO nanorods were synthesized by a hydrothermal method on homoseed layers deposited using atomic layer deposition (ALD) and heat-treated at various temperatures ranging from 200 to 600 °C in air. The effect of the annealing temperatures on nanorod formation was investigated. With increasing temperature, the microstructure of the ZnO seed layers changed from nanocrystals to coarse polycrystals with a preferred orientation, which led to an increase in the length and diameter of the solvothermally Atomic layer depositionZnO Nanorods Thermal treatments