Thickness dependence on crystalline structure and interfacial reactions in HfO₂ films on InP (001) grown by atomic layer deposition

The crystalline structure and interfacial reactions in HfO₂ films grown on InP (001) substrates was investigated as a function of film thickness. High resolution transmission electron microscopy and x-ray diffraction measurements were used to investigate changes in the crystalline structure of the HfO₂ films. As the thickness of the HfO₂ increased, the crystal structure was transformed from monoclinic to tetragonal, and the interfacial layer between the HfO₂ film and the InP substrate disappeared. High resolution x-ray photoelectron spectroscopy was also applied to confirm the existence of an interfacial chemical reaction in HfO₂ /InP. An interfacial self-cleaning effect occurred during the atomic layer deposition process, resulting in a clear interface with no indication of an interfacial layer between the HfO₂ film and the InP surface. Finally, the crystallization process in the HfO₂ films was found to be significantly affected by the interfacial energy.