Be掺杂纤锌矿ZnO电子结构的第一性原理研究

First-principle study of electronic structure of Be-doping wurtzite ZnO

采用密度泛函理论结合投影缀加波方法,对Be掺杂导致ZnO禁带宽度增加的机理进行了研究.通过对掺杂前后电子能带结构、总态密度以及分态密度的计算和比较,发现导带底(CBM)是由Be2s电子与Zn4s电子共同控制;而BexZn1-xO价带顶(VBM)始终由O2p电子占据.随着掺杂量的增加,决定带隙宽度的CBM的位置上升,同时VBM的位置下降,从而导致了带隙的变宽,出现了蓝移现象.此外,Be掺杂会使晶胞发生压缩,这种压应变也是导致BexZn1-xO禁带宽度变宽的原因之一.

Using the density-functional theory combined with the projector augmented wave method, we have investigated the electronic structure of Be-doping wurtzite ZnO. The band structure, total density of states and partial density of states of Bex Zn1-x O are presented and show that the valence band maximum （VBM） is determined by O 2p electrons and the conduction band minimum （CBM） is occupied by the hybrid Be 2s and Zn 4s electrons. The energies of CBM increase and the energies of VBM decrease with increasing Be-doping concentrations. Both effects lead to broadening of the band gap. Furthermore, it was found that Be-doping can cause compressive strain in the crystal structure, which also widens the band gap.