Zn空位对Al-P共掺杂ZnO电子结构影响的第一性原理计算

采用第一性原理平面波赝势法计算ZnO（Al，P）体系的晶格参数和电子结构，重点分析Zn空位对体系晶体结构、形成能、态密度的影响.计算结果表明：Al和P共掺杂过程中，Al_Zn-P_Zn有更低的形成能，能带分析呈现n型.并随着Zn空位浓度的增大使得掺杂后的晶胞体积减小，晶格常数c先增大后减小.存在Zn空位的掺杂体系形成能比Al_Zn-P_O掺杂体系低，体系较稳定.能带分析呈现p型趋势.Al和P以1∶2的比例掺杂时，体系的形成能降低，体系更稳定；同时，比较1个V_Zn和2个V_Zn的Al_Zn-P_Zn共掺杂体系的能带结构发现，随着Zn空位浓度增大，带隙增大，体系p型化特征增强.Al_Zn-2P_Zn共掺杂体系带隙减小为0.56 eV，更有利于提高其导电性质.然而出现2V_Zn后，带隙增大为0.73 eV，小于本征ZnO带隙，p型化程度更强烈；此外态密度分析表明2V_Zn的Al_Zn-2P_Zn共掺杂使得态密度更加分散，更多的电子穿过费米能级使得p型化更明显.因此，将Al/P按1∶2的比例共掺且Zn空位增至2个时，可以获得导电性能更好的p型ZnO.

Effects of Zinc Vacancies on Electronic Structure of Al-P Co-doped ZnO:First-principles Calculations

With pseudo-potential plane-wave based on density functional theory (DFT), effects of zinc vacancies on ZnO lattice parameters and electronic structure of Al-P co-doped were studied. Formation energy, density of states are analysed. It shows that Al_Zn-P_Zn has the lowest formation energy and presents n-type in the process of co-doping. Presence of zinc vacancies make cell volume decrease, and lattice constant c increase and decreases as concentration of zinc vacancies increase. According to formation energy of co-doping, formation of zinc vacancies system is more stable than Al_Zn-P_O. System with Al and P ratio of 1:2 co-doping can reduce formation energy and become more stable. With comparisons of band structure of V_Zn and 2V_Zn, it is found that band gap increased with zinc vacancies increasing, which makes p-type ZnO more obvious and enhances conductivity of Al_Zn-2P_Zn co-doping systems. However, for Al_Zn-2P_Zn co-doping of 2V_Zn, it shows great superiority of p-type. According to state density analysis, Al_Zn-2P_Zn of 2V_Zn makes the state density more diffuse, and go through the Fermi level, which leads to formation of obvious p-type. As a result, better p-type ZnO can be obtained by controlling Al/P in proportion of 1:2 co-doing with zinc vacancy to 2V_Zn.