Surface, structural and optical properties of sol-gel derived HfO2 films

Abstract The surface, structural and optical properties of sol-gel derived HfO2 films have been investigated. The water droplet contact angles reached constant values between 80 and 100° after the films were left for 1–4 days in air at ambient temperature, indicating that the film surface exhibited hydrophobicity. Hydrophobicity was maintained even after the films were treated with organic solvents. Scanning electron microscopy and atomic force microscopy observation showed that the film surface was smooth and uniform. The HfO2 in the films crystallized to the monoclinic phase at firing temperatures between 500 and 550°C and no other phases were observed to 900°C. The refractive index and optical gap of the films were 1.88–1.93 and 5.1 eV, respectively.