Process optimization and optical property of HfO₂ thin films prepared with hafnium material

The optical properties of HfO₂ thin films are greatly influenced by the preparation process factors. Using hafnium metal as the raw material and oxygen as the reaction gas, the monolayer HfO₂ thin films were deposited on quartz glass substrates by electron-beam thermal evaporation technology. The effects of evaporation current, working pressure and deposition temperature on its optical properties and laser-induced damage threshold were studied through orthogonal experiments. The spectral transmittance of monolayer HfO₂ thin films were measured by a spectrophotometer, its refractive index and extinction coefficient were measured by an ellipsometry, and its laser-induced damage threshold was measured by laser-induced damage test system. The research finds out that the evaporation beam is the most important factor affecting the optical properties and laser-induced damage threshold of monolayer HfO₂ thin films, the working vacuity is the secondary factor, and the influence of deposition temperature is not significant. The optimal process parameters affecting the optical properties of HfO₂ thin films were obtained through the process optimization, The evaporation beam is 170 mA, the working pressure is 1.8×10⁻² Pa, and the deposition temperature is 160 ℃. The prepared HfO₂ thin films at this process parameters have a refractive index of 1.889 6 at 1 064 nm, an extinction coefficient of 3.07×10⁻⁵ at 1 064 nm, and a laser-induced damage threshold of 23.1 J·cm⁻² at a single pulse energy of 1 064 nm.