The effects of O vacancies upon the electronic structure of silicon dioxide and the hole tunneling current were investigated by using first-principles calculations. A level which was related to the O vacancy was found to be nearly 2.0eV from the top of the valence band within the band-gap of an α-quartz super-cell with one O vacancy. Defect-assisted hole (electron) tunneling currents were then calculated. The results showed that the hole tunneling current would be predominant for a thinner oxide thickness at low oxide fields, and the contribution of trap-assisted hole tunneling to the total tunneling current decreased with oxide thickness and oxide field increase. It was concluded that the effects of O vacancies upon the hole tunneling current became smaller with larger oxide thicknesses and higher electric fields.

First-Principles Study of the Effects of Oxygen Vacancy on Hole Tunneling Current. L.F.Mao: Microelectronics Reliability, 2007, 47[8], 1213-7