The optical properties of hydrophilic Hf-doped HfO2 nanoceramic films

The Hf-doped HfO2 (HfO2:Hf) nanoceramic films were deposited by simultaneous rf magnetron sputtering of HfO2 and dc magnetron sputtering of Hf. By doping with Hf, the lowest oxidation state of Hf (Hf0+) presented preferentially and changed the hydrophobicity of HfO2 film into hydrophilicity. On comparing with the HfO2 film, the optical transmission of HfO2:Hf film was higher and strongly increased with pressure, especially in the ultraviolet region and near infrared region. At higher pressure, HfO2:Hf film exhibited better hydrophilicity, higher linear refractive index and lower stress-optical coefficient.