A study was made of the influence of multiple oxygen vacancy traps in the percolated dielectric upon the post-breakdown random telegraph noise digital fluctuations in HfO2-based metal-oxide-semiconductor transistors. The electrical characterization results indicated that these digital fluctuations were triggered only beyond a certain gate stress voltage. First-principles calculations suggested that the oxygen vacancies were responsible for the formation of a sub-band in the forbidden band gap region, which affected the triggering voltage for the random telegraph noise fluctuations and led to a shrinkage of the HfO2 band gap.
Role of Oxygen Vacancies in HfO2-Based Gate Stack Breakdown. X.Wu, D.B.Migas, X.Li, M.Bosman, N.Raghavan, V.E.Borisenko, K.L.Pey: Applied Physics Letters, 2010, 96, 172901