Pulsed laser deposition of a ZnO:Eu³⁺ thin film: Study of the luminescence and surface state under electron beam irradiation

A highly c-axis orientated Eu³⁺ doped ZnO (ZnO:Eu³⁺) thin film was successfully deposited by pulsed laser deposition in an oxygen working atmosphere. The structure, morphology, chemical analysis and luminescence properties of the sample were investigated. The effect of electron beam irradiation on the surface state, chemical and luminescence properties of the sample were studied. Successful incorporation of Eu³⁺ ions in the ZnO matrix was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. XPS measurements revealed traces of the divalent (Eu²⁺) on the film surface while the trivalent (Eu³⁺) oxidation state in the bulk of the film. XPS depth profile confirmed that the film contained excess oxygen throughout the film. The film exhibited exciton and defect emission of ZnO as well as 4f – 4f characteristic emission of Eu³⁺ ions superimposed on the defect emission when excited at 325 nm using a He-Cd laser. Whereas only 4f – 4f characteristic emission of Eu³⁺ ions was recorded when the film was excited at 464 nm and also when excited with the electron beam. XPS high resolution spectra of the O 1s peak confirmed the creation of new defects during electron beam In general, ZnO:Eu³⁺ films show potential for applications as a source of red light in optoelectronic devices.