Influence of different oxidants on the band alignment of HfO2 films deposited by atomic layer deposition

Based on X-ray photoelectron spectroscopy (XPS), influences of different oxidants on band alignment of HfO2 films deposited by atomic layer deposition (ALD) are investigated in this paper. The measured valence band offset (VBO) value for H2O-based HfO2 increases from 3.17 eV to 3.32 eV after annealing, whereas the VBO value for O3-based HfO2 decreases from 3.57 eV to 3.46 eV. The research results indicate that the silicate layer changes in different ways for H2O-based and O3-based HfO2 films after the annealing process, which plays a key role in generating the internal electric field formed by the dipoles. The variations of the dipoles at the interface between the HfO2 and SiO2 after annealing may lead the VBO values of H2O-based and O3-based HfO2 to vary in different ways, which fits with the variation of flat band (VFB) voltage. (condensed matter: electronic structure, electrical, magnetic, and optical properties)