The electronic structure and relative stability of monoclinic, tetragonal, and cubic phases of with Ti doping in the range of 3.125%–37.5% are studied by means of first-principles calculations. The dielectric response, and electron and hole trapping properties of Ti-doped monoclinic are calculated using a hybrid density-functional B3LYP. The incorporation of Ti into induces higher polarizability of Hf and O ions, accompanied by an increase in the static dielectric constant and softening of phonon modes. However, the Ti ions serve as deep electron traps inducing localized levels in the gap and, at high Ti concentrations, the conduction-band offset with Si is effectively reduced by about 1.5 eV.
- Received 14 July 2008
©2009 American Physical Society