The effect of seed layer thickness on alignment and morphology of ZnO nanorods

Thin films of ZnO of 20, 40,160 and 320 nm thickness were deposited on Si (100) substrates by rf-magnetron sputtering and then nanorods were grown on the seed layer at 95 °C for 2 h. The ZnO nanorods were synthesized in C 6H 12N 4 and Zn (NO 3) 2·6H 2O solution by a hydrothermal method and the effect of seed layer thickness on the alignment, diameter, density and growth rate of nanorods was studied. The results revealed that the alignment of nanorods depended on crystallinity, grain size and roughness frequency of the sputtered seed layer, so that, with increase of seed layer thickness, crystallinity improved. In addition the grain size increased and the roughness frequency decreased and hence alignment and diameter of nanorods increased. Finally, we present a model for the effect of seed layer thickness on the alignment and diameter of the nanorods. ► Model for seed layer thickness effect on alignment and diameter of nanorods. ► Substrate can affect the growth rate of nanorods. ► Nanorods alignment depends on seed layer roughness, crystallinity and grain size.