First-Principles Study on Properties of the Native Defects in Al2O3(110) Surface

Using the CASTEP module in Materials Studio software, the native defect model structures including O vacancy and Al vacancy in Al2O3(110) surface were designed and constructed. Through first-principles based on density functional theory (DFT) and pseudo potential method, the Al2O3(110) model structures were optimized. Formation energy, energy state structure, electric density and electron population of defect structures and primitive cell were calculation. Effect of O vacancy and Al vacancy on Al2O3 properties could be analyzed and probed. The results showed that formation energy of O vacancy is only 0.06 eV, which is significantly less than that of Al vacancy (2.99 eV). This indicates that the formation of O vacancy is more easily to produce. O vacancy defects reduce electronic energy in Al2O3(110), and make its conductivity become poorer. The impact of Al vacancy defects on conductivity are opposite. The influence of aluminum vacancy defects on electron density in Al2O3(110) is more than that of oxygen vacancy; oxygen vacancy increases the electronegativity around O atoms, and weakens electropositivity around Al atoms the electricity, which makes the top of energy band structure move down. The calculation results provide a theoretical guidance for the formation of functional anodic oxidation films of Al.