ZnO and ZnS nanodots deposited by spray methods: A versatile tool for nucleation control in electrochemical ZnO nanorod array growth

ZnO and ZnS nanodots deposited by simple, non-vacuum ultrasonic spray methods, spray pyrolysis and ion layer gas reaction, are used to control the nucleation and thereby the morphology of electrochemically grown ZnO nanorod arrays. The ZnO nanodot density and subsequently the density of electrochemically deposited ZnO nanorods is increased by increasing the aerosol flow and decreasing the substrate temperature during ZnO nanodot deposition. By increasing the substrate temperature during ZnO nanodot deposition, moreover, the nanorod tilt with respect to the substrate (normal) can be decreased. To tune the density of electrochemically deposited ZnO nanorods to lower values compared to growth on the bare substrate, ZnS nanodots are used to block energetically favorable nucleation sites for electrochemical ZnO nanorod growth and thereby reduce the ZnO nanorod density.