H-related defect complexes in HfO2:: A model for positive fixed charge defects

Based on first-principles theoretical calculations, we investigate the hydrogenation effect on the defect properties of oxygen vacancies (V-O) in HfO2. A defect complex of V-O and H behaves as a shallow donor for a wide range of Fermi levels, with a positive charge state, and this complex is energetically stable against its dissociation into V-O and H. We suggest that the V-O-H complex is responsible for the formation of positive fixed charges, which neutralize negative fixed charges during the postannealing process of SiOx/HfO2 stack. (C) 2004 American Institute of Physics.