Preparation and characterizations of ZnO films for photoelectronic applications

Surface photovoltage of semiconductors depends strongly on their electronic structures, in particular, their Fermi energy level. This offers a possibility to characterize photoelectronic behavior using the Kelvin probe structure by measurements of Work function (WF). In this paper, ZnO films were prepared using the CVD method and theirs microstructures and morphology were characterized using the XRD and SEM. Furthermore, photovoltage evolution and WF of selected ZnO samples were measured using a scanning Kelvin probe (SKP) system. It is found that the surface photovoltage and its time-resolved evolution process as well as the energy level structure of ZnO films can be correlated to WF very well. The present study therefore provides a simple and practical methodology for the characterization of photovoltaic behavior of semiconductors films.