First-principles study of electronic structure and electron energy-loss-spectroscopy (EELS) of transition-metal aluminates as high-k gate dielectrics

We study the electronic structure and electron energy loss function of different transition-metal (Y, Sc, Zr, Hf and Ta) aluminates using density functional theory (DFT) and local density approximation (LDA). The transition metals are substituted favorably at the octahedral Al sites in the α-alumina system. Y and Sc introduced shallow unoccupied d-states near the conduction band edge. Using the calculated orbital resolved partial p-DOS, we have investigated the oxygen K-edge and compared to the experimental results. In addition, the energy-loss-functions were calculated in the low energy-loss region directly reflects the collective electron excitations (plasmons) and single valence electron excitation in to unoccupied states of the conduction band.