第一性原理研究Te-N共掺p型ZnO

采用基于密度泛函理论的第一性原理赝势法对Te-N共掺杂ZnO体系的晶格结构、 杂质态密度和电子结构进行了理论分析.研究表明, N掺杂引起晶格收缩,而Te的掺入引起晶格膨胀, 从而减小晶格应力促进N的掺杂,并且Te由于电负性小于O而带正电, Te在ZnO中作为等电子施主而存在.研究发现, N掺杂体系中在费米能级附件形成窄的深受主能级, 而Te-N共掺体系中, N杂质带变宽,空穴更加离域,同时,空穴有效质量变小,受主能级变浅, 更有利于实现p型特性.因此, Te-N共掺有望成为一种更为有效的p型掺杂手段.

First-principles study of p-type ZnO by Te-N codoping

The crystal structure, density of states and electronic structures of Te-N doped ZnO are investigated from the first-principles pseudo-potential approach based on density functional theory. It is found that the incorporation of N into ZnO induces contraction of lattice, while Te incorporation will cause expansion of lattice. Thus, the co-doping of both Te and N is conducible to the incorporation of N with minimum lattice strain. Besides, Te atoms is positively charged because the electronegativity of Te is smaller than that of O. Consequently, Te atom is expected to act as an isoelectronic donor in ZnO. Moreover, the acceptor level of N doped ZnO is narrow and deep. While in the Te-N doped ZnO system, N-impurity bandwidth at the top of valence band becomes larger, while tends to delocalize the hole. Meantime, the system obtains shallower acceptor levels and lighter mass of acceptors. The results suggest that the codoping of Te-N is an effective p-type doping method in ZnO.