Influence of RF power on the structure and optical properties of sputtered hafnium dioxide thin films

Hafnium dioxide (HfO2) thin films were prepared by radio frequency (RF) magnetron sputtering at various RF powers. The influence of RF power on the structure and optical properties of the HfO2 thin films were studied systematically by X-ray diffraction (XRD), ultraviolet-visible transmission spectrum and Fourier transform infrared (FTIR) spectrum. The results show that the thin films are polycrystalline, the crystallization is improved and the crystallite size has its minimum value for the thin film deposited at the RF power of 110 W. The refractive index and band gap energy of the thin films both increase firstly and then decrease with the increased RF power. The further study reveals that the antireflective effect in certain infrared waveband, such as 3–5 μm and 8–12 μm, can be achieved in the HfO2/Si/HfO2 system, indicating an excellent infrared antireflective coating of HfO2 thin film.