Surface wettability, morphology and optical characteristics of HfO2 films grown systematically by electron beam evaporation

The study reports the fabrication of hafnium oxide (HfO2) thin films on glass and silicon (Si) substrate using electron beam evaporation technique. The deposition of films was carried out in a stepwise approach, in which a run deposited the thickness of ~ 100 nm, and subsequently, the overall thickness was achieved by repeating the deposition process to achieve better quality films. Initially, films were amorphous and were subjected to a thermal treatment process above 400 °C temperature to assess the crystallinity. The structure of these films was analyzed by X-ray diffraction (XRD) indicating crystalline nature of the annealed films. The surface morphology examined using field emission scanning electron microscopy (FE-SEM) revealed a dense microstructure with round-shaped grains with a diameter of 30–50 nm. The average surface roughness of HfO2 films was achieved in the range of 7–9 nm measured using optical profiler. The optical studies having UV–Vis–NIR range indicated high transparency in visible region (average transmission ~ 85%). The film thickness was evaluated using envelope method, and compared with the thickness obtained from cross-sectional SEM and reflectometer results. The surface wettability measurement of the HfO2 thin film was performed using a drop shape analyzer that indicates the hydrophobic nature of 500 nm thin films over glass and Si substrate. The observations showed that the developed single-layer thin film can be a promising choice in optical, anti-reflection, protective, optoelectronics, and so forth, applications.