Influence of pH on structural, morphological and optical properties of chemically deposited nanocrystalline ZnO thin films

In the present work, a simple and cost effective successive ionic layer adsorption and reaction method was adopted to grow highly oriented crystalline ZnO nanorods (NRs). The ZnO NRs were grown over glass substrates by varying the pH. The surface morphology studies show that the dimension and orientation of ZnO NRs are influenced by varying the pH conditions. The SEM analysis reveals that the ZnO NRs grow vertically with perfect wurtzite hexagonal shape with a diameter range from 300 nm to 1 mu m at optimized pH concentration. The XRD patterns of the ZnO NRs exhibit high crystalline orientation of ZnO wurtzite structure with a preferential (101) plane orientation. Optical spectra recorded using UV-Vis spectrophotometer on ZnO rods show that the optical band gap decreases with increase in pH of the solution. This simple and integrated approach is expected to lead to a cost effective and convenient way towards large scale growth of ZnO rods with subsequent interest in nano-based biosensor applications in future.