Influence of La on electronic structure of α-Al2O3 high k-gate from first principles

The theoretical effects of La on electronic structure of Al2O3 high k-gate have been studied by first principles. The electronic properties of pure α-Al2O3 and La aluminates (Al2−xLaxO3, x = 0.50) were studied by using the density functional theory. The calculations were performed by the full potential-linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA). The calculated electronic structure and charge density yield a band gap of ∼6.4 eV for pure α-Al2O3 (without empirical correction factor) at the Γ point in the Brillouin zone, fairly close to experimental values. The substitution of La reduces the band gap to ∼3.6 eV for Al1.5La0.5O3. The calculated density of states (DOS) of α-Al2O3 is in good agreement with recent experimental XPS and XES data.