Structural evolvement of ZnO nanoporous films fabricated using prolonged electrodeposition under pulsed voltages

ZnO nanoporous films consisting nanocrystals on ITO-coated glass substrates were prolongedly electrodeposited under pulse voltages in zinc nitrate solution at room temperature. Their structures were found to be determined by experimental parameters, especially, the voltage and the deposition time. On the basis of the structural characterization, the growth mechanism was proposed as a combined growth process: the competitive growth between lateral overgrowth and nanovoid formation. The structural evolvement is believed to be due to the decrease of surface potential with deposition time, leading to the formation of a quasi-two-layer structure. The revealed mechanism here could be helpful to understand the growth and corresponding properties of ZnO films as well as their nanostructures. -- Highlights: → ZnO nanoporous films were prolongedly electrodeposited under pulse voltages. → The film consists of a quasi-two-layer structure. → Competitive growth between lateral overgrowth and nanovoid formation. → Decrease of surface potential with deposition time.