First principles calculation of electronic structures of Si-doped Al₂O₃

The first-principles methods are used to study the band structures and the densities of states of the pure Al₂O₃ and the Si_0.167Al_0.833O_1.5, Si_0.25Al_0.75O_1.5 of Si-doped Al₂O₃. It is shown that the energy gap decreases as the proportion of Si increases in Al₂O₃ crystal and it is reduced to 2.5 eV in the crystal system of Si_0.25Al_0.75O_1.5. These indicate that the Si-doped Al₂O₃ is semiconductor material. However, in the Si-doped system, there are several band energies across the Fermi level, predicting that the doped system has special photoelectric properties. Comparing the total density of states of the pure Al₂O₃ with those of Si_0.167Al_0.833O_1.5 and Si_0.25Al_0.75O_1.5 crystal systems, it is found that the valence band and the conduction band of the Si-doped Al₂O₃ move to the low-energy region. (authors)