ZnO:Sb掺杂机理的第一性原理研究

为了研究ZnO:Sb的掺杂机理,本文运用第一性原理密度泛函理论计算了理想纤锌矿ZnO和SbO 、SbZn 、SbZn-2VZn三种Sb掺杂ZnO晶体模型的几何结构、能带结构和电子态密度.计算结果表明:sb的掺人使得晶格发生不同程度的膨胀,其中以SbZn-2VZn复合缺陷模型的膨胀最小,键长最短,说明此结构的化学稳定性最高.通过能带和态密度的分析可知,ShO和SbZn模型存在不合理性,而SbZn-2VZn复合缺陷中的VZn可以使价带产生非局域化空穴载流子.定量计算进一步确认了SbZn-2VZn构型的可填充电子数最多,合理解释了晶体导电性的提高.形成能计算表明,在富氧条件下SbZn-2VZn的形成能最低,说明在富氧条件下掺杂Sb更有利于实现ZnO的p型化.

First-principle Study on the Doping Mechanism of ZnO: Sb

The doping mechanism of ZnO∶Sb was investigated through the calculation of the geometric structures,band structures and density of states of wurtzite ZnO and three types of Sb doped ZnO models(SbO,SbZn and SbZn-2VZn) by the first-principles density functional theory.The calculated results show that Sb doping could give rise to the expansion of ZnO lattice to some extent,and SbZn-2VZn complex model has the least expansion and the shortest bond length,indicated that this structure had the highest chemical stability.Based on the analysis of energy band and the density of states,it is learnt that it is irrational for SbO and SbZn models,while the presence of VZn in SbZn-2VZn complex defects can introduce nonlocal hole carriers in valence band.The quantitative calculations also confirm that SbZn-2VZn complex can hold the most electrons.This can explain why the electrical conductivity of ZnO crystal can be improved.According to the calculated results of formation energy,it is known that SbZn-2VZn complex has the lowest formation energy under O-rich condition.It suggests that O-rich condition is more beneficial for the p-type doping ZnO.