Defect states in the high-dielectric-constant gate oxide HfSiO4

Hafnium silicate has a high dielectric constant and is a leading candidate to act as a gate dielectric. The defect energy levels have been calculated. The oxygen vacancy is found to give rise to Si-like levels which lie within the band gap of Si. The vacancy states are very localized and are localized on the neighboring Si sites. A second defect level high in the oxide gap is localized on the Hf sites. The behavior of ZrSiO4 is similar. (c) 2007 American Institute of Physics.