Role of Substrate Roughness in ZnO Nanowire Arrays Growth by Hydrothermal Approach

The role of substrate roughness in ZnO nanowire（NW） arrays hydrothermal growth has been systematically studied.Six silicon substrates with different roughness by chemical etching have been selected to grow ZnO NW arrays hydrothermally after sputtering 5-nm-thick ZnO seed layer as catalyst.The as-grown samples reveal that average diameters and number densities of ZnO NW arrays are inversely proportional to the increasing substrate roughness observed by atomic-force microscopy and scanning electron microscopy.Furthermore,the theoretically derived equations based on nucleation with the Gibbs free energy to describe relations of substrate roughness versus average NW diameter and NW number density match well with experimental results.Research results in this paper can be used to control the number density and the average diameter of ZnO NW arrays by alternating substrate roughness.