Phase transformations in hafnium dioxide thin films grown by atomic layer deposition at high temperatures

Abstract High-temperature cubic phase of HfO2 was observed by reflection high-energy electron diffraction in nanocrystalline thin films grown by atomic layer deposition from HfCl4 and H2O at substrate temperatures of 880–940°C. The phase was formed at properly chosen precursor doses and it was observed on the surface of films, which according to X-ray diffraction data consisted of monoclinic HfO2. The thickness of the surface layer, in which the cubic phase appeared, was estimated to be 5–10 nm. According to Auger electron spectroscopy data, formation of the cubic phase was accompanied with an increase in the ionicity of O–Hf bonds.