Effect of substrate on the structure and optical properties of ZnO nanorods

Crystalline ZnO nanorods have been grown on various substrates by a low cost aqueous chemical growth technique. The effect of substrates on the properties of ZnO nanorods has been investigated systematically. The nanorods deposited on silicon are observed to be structurally and optically different from that grown on GaN. Due to a higher rate of nucleation on the silicon substrate, the surface density of nucleation centres is very high. As a result, we get randomly oriented nanorods on the silicon substrate. Arrays of standing, single crystalline nanorods could be deposited on n-GaN/Al₂O₃ and p-GaN/Al₂O₃ substrates due to a good lattice match between GaN and ZnO. In order to grow standing nanorods on ITO, we had to deposit a layer of nanoseeds of ZnO on the ITO/quartz substrate by electro-deposition in the presence of a surfactant.