Incorporation of F into HfO2 with O vacancies was investigated by using first-principles calculations. It was shown that atomic F could efficiently passivate the neutral O vacancy with excess energies of 4.98 and 4.39eV for threefold- and fourfold-coordinated O vacancy sites, respectively. The introduction of F elevated the vacancy-induced state into the conduction band by transferring the neutral vacancy state to a positively charged state, and thus removed the gap state which caused trap-assisted tunneling. The HfO2 band gap was not narrowed following F incorporation.

First Principles Calculations of Oxygen Vacancy Passivation by Fluorine in Hafnium Oxide. W.Chen, Q.Q.Sun, S.J.Ding, D.W.Zhang, L.K.Wang: Applied Physics Letters, 2006, 89[15], 152904 (3pp)