Spectroscopic investigation of the electronic structure of thin atomic layer deposition HfO2 films

The electronic structure of HfO2 thin films is investigated employing resonant photoelectron spectroscopy (resPES). The detailed analysis of the O1s resonance profile enables the determination of the partial density of states for the valence and the conduction bands as well as the electronic band gap to be 6.2 eV. The position of the charge neutrality level is evaluated. Thereby, it is demonstrated that the resPES data are able to combine information both for the valence as well as for the conduction band states. In addition, evidences for intrinsic in-gap states attributed to polaronic and charge transfer states are given. Electronic charges within the atomic layer deposition-HfO2 films are identified, pointing out that the amount of charges is essential to determine the accurate position of the surface potentials.