“…The nanostructures like nanotubes, nanorods, nanowalls, nanofibers and high-quality undoped and doped ZnO thin films have been grown with plasma-assisted molecular beam epitaxy, vapor transport deposition method, vacuum arc deposition metal organic chemical vapor deposition (MOCVD), sol–gel process, and spray pyrolysis [9, 10]. Such nanotubes, nanowires, nanoribbons, and nanofibers have deserved special attention for their potential applications in applied fields such as field emission displays, optical waveguides, solar cells, ultraviolet photodetectors, optical switches, and gas sensing [1–8]. The chemical bath deposition and sol–gel technique are also well known methods of preparation of ZnO thin films.…”