Ag-N共掺p型ZnO的第一性原理研究

采用基于密度泛函理论的第一性原理赝势法对Ag-N共掺杂ZnO体 系以及间隙N和间隙H掺杂p型ZnO: (Ag, N)体系的缺陷形成能和离化能进行了研究. 结果表明, 在Ag_Zn和N_O所形成的众多受主复合体中, Ag_Zn-N_O受主对不仅具有较低的缺陷形成能同时其离化能也相对较小, 因此, Ag_Zn-N_O受主对的形成是Ag-N共掺ZnO体系实现p型导电的主要原因. 研究发现, 当ZnO: (Ag, N)体系有额外间隙N原子存在时, Ag_Zn-N_O受主对容易与N_i形成Ag_Zn-(N₂)_{m O}施主型缺陷, 该施主缺陷的形成降低了Ag-N共掺ZnO的掺杂效率因而不利于p型导电. 当间隙H引入到ZnO: (Ag, N)体系时, H_i易与Ag_Zn-N_O受主对形成 受主-施主-受主复合结构(Ag_Zn-H_i-N_O), 此复合体的形成不仅提高了Ag_Zn-N_O受主对在ZnO中的固溶度, 同时还能使其受主能级变得更浅而有利于p型导电. 因此, H辅助Ag-N共掺ZnO可能是一种有效的p型掺杂手段. 关键词： p型ZnO 缺陷形成能 受主离化能 第一性原理

First-principles study of Ag-N dual-doped p-type ZnO

The formation energies and ionization energies of Ag-N dual-doped ZnO and interstitial N and H monodoped ZnO:(Ag,N) are investigated from the firstprinciples pseudo-potential approach based on density functional theory. It is found that Ag_Zn-N_O accepter pair has lower formation energy and ionization energy than Ag-N related to acceptor clusters, which demonstrates that the p-type conductivity of Ag-N dual-doped ZnO system is mainly attributed to the formation of the accepter pairs. Moreover, when ZnO:(Ag,N) system has additional N atoms in some interstitial sites of ZnO crystal, interstitial N atom and Ag_Zn-N_O accepter pair prefer to bind together to form Ag_Zn-(N₂)_O donor complex which lowers doping efficiency, which is not conducive to p-type conductivity. For H doping in the ZnO:(Ag,N) system, the interstitial H atoms also prefer to bind to the Ag_Zn-N_O accepter pair, forming acceptor-donor-acceptor (Ag_Zn-H_i-N_O) triplet, which not only enhances the incorporation of acceptors (Ag_Zn-N_O) but also gives rise to a shallower acceptor level in the band gap in p-type ZnO crystal. Thus, it is suggested that H-assisted Ag-N codoping is an effective method of p-type doping in ZnO.
Keywords： p-type ZnO defect formation energy acceptor ionization energy first principles