Electronic properties of defects in polycrystalline dielectric materials

Grain boundaries have been implicated in current leakage and dielectric breakdown of CMOS devices. We calculate the electronic properties of oxygen vacancy defects near grain boundaries in the dielectric insulators MgO and HfO2 using first principles methods. In both materials we find that oxygen vacancies favourably segregate to grain boundaries, in various charge states. Their electronic properties are different from their counterparts in the bulk. At increased concentrations, such defects at grain boundaries may play a key role in processes such as electron tunneling, charge trapping and dielectric breakdown in electronic devices.