B-N共掺杂改善p型ZnO的理论分析

采用基于密度泛函理论的第一性原理赝势法对B缺陷在ZnO中的存在形式进行了理论分析,对B-N共掺杂ZnO体系的晶格结构、杂质形成能、杂质态密度及电子结构进行了系统的研究.研究表明,B缺陷在掺杂体系中主要以BZn的形式存在,这种结构会引起相应的晶格收缩;研究发现与以往的N掺杂相比,共掺结构具有更低的杂质形成能和更高的化学稳定性,因此更加适合掺杂.此外,共掺能够形成更低的受主能级,因而减小了受主的杂质电离能,提高了受主态密度;研究显示共掺结构下的杂质N原子与体相Zn原子之间的键合能力提高,受主原子得电子的能力增强,因此B-N共掺有望成为一种更为有效的p型掺杂手段.

Theoretical analysis on the improvement of p-type ZnO by B-N codoping

The formation of B defect, the crystal structure, formation energies, density of states and electronic structure of B-N codoped ZnO were studied using first-principles pseudo-potential approach of the plane wave based upon the density functional theory(DFT). The study reveals that most of the B atom will present in as-doped ZnO in the form of B_(Zn), which could result in the shrinkage of ZnO unitcell. Compared with N doped ZnO, B-N codoped ZnO has a lower formation energy, correspondingly a higher chemical stability, so its formation is more realizable. Moreover, the acceptor levels of B-N doped ZnO are shallower, resulting in a decreased ionization energy as well as a higher acceptor density. The bonding power of Zn-N is increased in as-doped ZnO, the properties of acceptors are also improved, therefore B-N codoping is expected to be a more efficient way to fabricate p-type ZnO.