Incorporation effect of Y2O3 on the structure and optical properties of HfO2 thin films

Abstract HfO 2 thin films doped with different concentration of Y 2 O 3 have been prepared on fused silica at substrate temperature of 160 °C using electron beam evaporation technique. The influence of doping ratio on the structure and optical properties was studied in this work. Several characterization techniques including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM), ellipsometer and spectrophotometer were used for the study of microstructure and optical properties of the films. From the results of XPS analysis, it is found that core level peak positions of Hf 4 f and O 1 s shift to lower binding energy, which was attributed to the structure change of the HfO 2 films after Y doping. The XRD and SEM results demonstrate that the concentration of Y 2 O 3 affects a lot on the crystallization of Y 2 O 3 doped HfO 2 (YDH) films. Cubic phase of the films appears as the doping ratio of Y 2 O 3 is over 8 mol% without any post annealing process. At the meantime, the optical band gap of the film is broadened with doping ratio of Y 2 O 3 increasing. An inverse correlation between band gap energy ( E g ) and refractive index ( n ) of the films is also found in our work.