Origin of traps and charge transport mechanism in hafnia
  In this study, we demonstrated experimentally and theoretically that oxygen vacancies are responsible for the charge transport in HfO$_2$. Basing on the model of phonon-assisted tunneling between traps, and assuming that the electron traps are oxygen vacancies, good quantitative agreement between the experimental and theoretical data of current-voltage characteristics were achieved. The thermal trap energy of 1.25 eV in HfO$_2$ was determined based on the charge transport experiments. 
D. R. Islamov (1 and 2), V. A. Gritsenko (1 and 2), C. H. Cheng (3),   A. Chin (4) ((1) Rzhanov Institute of Semiconductor P...
cond-mat.mtrl-sci