Abstract: 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.

Key words: Al-P co-doping, first principles, zinc vacancies, electronic structure