【摘要】 建立了一种 2× 2α Al2 O3 (0 0 0 1)基片表面吸附ZnO模型 ,在周期边界条件下的k空间中 ,采用基于密度泛函理论的局域密度近似平面波超软赝势法 ,对α Al2 O3 (0 0 0 1)基片表面结构及其ZnO分子在表面最初吸附生长位置进行了计算研究。由于较大的表面弛豫 ,使得氧原子全部暴露于基片最外表面 ,明显地表现出O原子电子表面态 ;驰豫后的表面能对ZnO分子产生较强的化学吸附 ,表面电子结构将发生明显的变化 ,其表面最优吸附生长点的方位正好偏离α Al2 O3 (0 0 0 1)表面氧六角对称 30° ;并计算了这些吸附生长点处Zn与表面O的结合能。更多还原

【Abstract】 A novel model has been developed to theoretically evaluate the adsorption of ZnO molecules and the initial growth of ZnO film on flat Al terminated surface of a 2×2 α Al 2O 3 (0001) substrates.In our ab initio calculation,periodic boundary condition in k space was assumed and the localized density of occupied orbitals was expanded and approximated with plane waves using ultra soft pseudo potential technique based on density functional theory.The results show that the electronic structure of the first surface layer,consisting exclusively of oxygen atoms because of strong surface relaxation,can be characterized by oxygen surface states.The relaxed surface strongly adsorbs ZnO molecules.The orientation of the preferential ZnO adsorption sites was found to be 30° away from the axis of the hexagonal symmetry of oxygen cells on the substrate surface.The calculated binding energy of Zn and O in the surface,252 kJ/mol,agrees well with experimental results,showing the nature of strong chemisorption.更多还原