Fabrication and characterization of potassium-doped ZnO thin films

Abstract

To develop a simple and effective method for fabricating a type of transparent p-type zinc oxide (ZnO) thin films, potassium-doped ZnO (K-ZnO) thin films were designed and prepared via molten-salt treatment (MST) in KNO3 for n-type ZnO thin film. The influence of filming temperature during sputtering and the followed MST on the crystalline structure, transmittance, bonding environment, surface morphology, and electrical property of the ZnO thin films has been investigated. The formed compound on quartz glass could be identified as wurtzite ZnO. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results show that the crystalline quality improves with raising the filming temperature. In addition, K 2p XPS spectra hint that the outside surface of ZnO thin films contains a certain amount of K, after MST for ZnO thin films. Compared with that of the followed MST, atomic force microscope (AFM) results also show that the filming temperature significantly affects surface morphology. More importantly, the ZnO thin films obtain p-type characteristics after MST for ZnO n-type thin films, with excellent transmittance and increased mobility.