摘要:
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AgZn和NO所形成的众多受主复合体中, AgZn-NO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, AgZn-NO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, AgZn-NO受主对容易与Ni形成AgZn-(N2)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, Hi易与AgZn-NO受主对形成受主-施主-受主复合结构(AgZn-Hi-NO),此复合体的形成不仅提高了AgZn-NO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。
Abstract:
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 AgZn-NO 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 AgZn-NO accepter pair prefer to bind together to form AgZn-(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 AgZn-NO accepter pair, forming acceptor-donor-acceptor (AgZn-Hi-NO) triplet, which not only enhances the incorporation of acceptors (AgZn-NO) 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.
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