  The dielectric breakdown at metal-oxide interfaces is a critical electronic
device failure mechanism. Electronic tunneling through dielectric layers is a
well-accepted explanation for this phenomenon. Theoretical band alignment
studies, providing information about tunneling, have already been conducted in
the literature for metal-oxide interfaces. However, most of the time materials
were assumed defect free. Oxygen vacancies being very common in oxides, their
effect on band lineup is of prime importance in understanding electron
tunneling in realistic materials and devices. This work explores the effect of
oxygen vacancy and oxygen di-vacancy at the Al/SiO2 interface on the band line
up within Density Functional Theory using PBE0 hybrid exchange and correlation
functional. It is found that the presence of defects at the interface, and
their charge state, strongly alters the band line up.
