Surface and chemical characterization of ZnO:Eu3+/Yb3+ spin coated thin films using SEM-CL and TOF-SIMS

The morphological properties of sol-gel spin coated ZnO:Eu3+(1 mol%)/Yb3+(7 mol%) thin films grown on Si(100) substrates are reported. The surface composition analysis of the ZnO films were investigated by using field emission scanning electron microscopy and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). TOF-SIMS was used to obtain depth profiles of the ZnO thin films at various features that formed on the surface during spin coating of the thin films. The films were also annealed at 1000 °C in order to determine if there was any inter-mixing of the Si substrate and the ZnO thin film when it was annealed. Two and three-dimensional (2D and 3D) depth profiles after annealing in both the positive and negative modes were measured. Analysis of the 3D images showed different features on the surface that appeared to be artificially embedded in the substrate, due to the experimental measuring setup of the TOF-SIMS. The details of these features are discussed. Inter-diffusion at the film/substrate was clear from the 3D profiles.