Structural, electronic and optical properties of the Al₂O ₃ doped SiO₂: First principles calculations

The doping effects of al₂o₃ on SiO₂ (α-cristobalite) have been studied by first principles calculations, with emphasis on the structural, electronic and optical properties. Compared to pure SiO₂ crystal, the electronic density of states (DOS) of the AhOi doped SiO; show significant changes. The electron energy states corresponding to the newly emerged sharp DOS peaks are found to exhibit localized characteristics, which are mainly attributed to the unsaturatedly bonded 2p orbitals of O atoms in the -[Al-O-Al]- linkages. The optical properties of the al₂O₃ doped SiO₂ are studied by calculating the frequency-dependent dielectric functions. The electric dipole moment induced by the electron states near the top of the valence band is found to have significant effect on the optical absorption spectrum.