Impact of Native Defects in the High Dielectric Constant Oxide HfSiO_4 on MOS Device Performance

Native defects in HfSiO_4 are investigated by first principles calculations. Transition levels of native defects can be accurately described by employing the nonlocal HSE06 hybrid functional. This methodology overcomes the band gap problem in traditional functionals. By band alignments among the Si, GaAs and HfSiO_4, we are able to determine the position of defect levels in Si and GaAs relative to the HfSiO_4 band gap. We evaluate the possibility of these defects acting as fixed charge. Native defects lead to the change of valence and conduction band offsets. Gate leakage current is evaluated by the band offset. In addition, we also investigate diffusions of native defects, and discuss how they affect the MOS device performance.