Based upon first-principles theoretical calculations, an investigation was made of the hydrogenation effect upon the defect properties of O vacancies (VO) in HfO2. A defect complex of VO and H behaved as a shallow donor for a wide range of Fermi levels, with a positive charge state, and this complex was energetically stable against its dissociation into VO and H. It was suggested that the VO–H complex was responsible for the formation of positive fixed charges, which neutralized negative fixed charges during the post-annealing of a SiOx/HfO2 stack.

H-Related Defect Complexes in HfO2 - a Model for Positive Fixed Charge Defects. J.Kang, E.C.Lee, K.J.Chang, Y.G.Jin: Applied Physics Letters, 2004, 84[19], 3894-6