Fe、F掺杂ZnO的电子结构和光学性质研究

The study on the electronic structure and optical properties of ZnO and co-doped with Fe-F

本文采用密度泛函理论框架下的第一性原理平面波超软赝势法,建立了Zn16O16、Zn15Fe1O16、Zn16O15F1、Zn15Fe1O15F1超晶胞,对掺杂前后ZnO超晶胞的能带结构分布、光学性质进行了计算与分析.计算结果表明:共掺杂Fe、F体系的形成能比单掺杂更小,稳定性更高;共掺杂体系的共价性最弱,更利于光生电子-空穴对的分离,且共掺杂体系的杂质能级数变得更为密集,电子更容易从低能级跃迁到高能级,进而提高光催化活性;Fe^3+的掺入导致费米能级进入导带,产生莫特相变,使之导电性增强;共掺杂体系的介电函数虚部向低能方向移动,在可见光区域的吸收峰值明显增大,说明Fe、F共掺杂是一种很好的光催化材料.

The electronic structure and optical properties of Fe-F co-doped ZnO are calculated by the first principle under the framework of density function theory with the plane wave supersoft pseudopotential method.The supercells of Zn16O16,Zn15Fe1O16,Zn16O15F1,Zn15Fe1O15F1 are constructed.The band structures and optical properties of ZnO before and after doping are calculated and analyzed.The results show that the co-doped system is easier to form than single-doped system and has higher stability;the covalent property of co-doped systems is weakest which is beneficial to separating the photo-generated hole-electron pairs.The impurity energy series of the co-doped system becomes more denser,and the electrons can easily jump from the low energy level to the high energy level which can improve photocatalytic abilities.The addition of Fe^3+results in the Fermi energy level entering the conduction band,producing Mott phase transition and enhancing its conductivity.The main peaks of the dielectric function imaginary part of the doping systems move to the low energy region and the absorption peak in visible light region is obviously increased,showing the co-doped of Fe and F is beneficial to improve the photocatalytic abilities.