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 degrees C for 2 h. The ZnO nanorods were synthesized in C6H12N4 and Zn (NO3)(2)center dot 6H(2)O 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. (C) 2011 Elsevier Ltd. All rights reserved.