Effects of substrate temperature on properties of HfO2, HfO2:Al and HfO2:W films

The HfO2 films were doped with Al (HfO2:Al) or W (HfO2:W) by simultaneous RF magnetron sputtering of HfO2 and DC magnetron sputtering of Al or W. According to XRD analysis, the monoclinic HfO2 film and a strong 1−11 preferential orientation were obtained as the substrate temperature increased to 500 °C. After doping with Al, a (300) preferential orientation in Al2O3 and the coexistence of monoclinic HfO2, orthorhombic HfO2 and Al2O3 were obtained at the substrate temperature of 500 °C. By increasing the substrate temperature, the coexistence of monoclinic HfO2 and tetragonal W5O14 was obtained in the HfO2:W film. Doping with Al or W could change the hydrophobicity of HfO2 films into the hydrophilicity. The HfO2:W films exhibited better hydrophilicity and lower average visible light transmission at higher substrate temperature. The hydrophilic HfO2:Al film showed higher average visible light transmission and higher linear refractive index at lower substrate temperature, favoring optical applications.