Cd掺杂纤锌矿ZnO电子结构的第一性原理研究

采用密度泛函理论结合投影缀加波方法，对掺杂Cd导致ZnO禁带宽度下降的机理进行了研究. 通过对掺杂前后电子能带结构，态密度以及分态密度的计算和比较，发现Cd_xZn_1-xO价带顶端(VBM)始终由O-2p占据；而导带顶端(CBM)则由Cd-5s与Zn-4s杂化轨道控制. 随着掺杂浓度的增加，决定带隙宽度的CBM的位置下降，同时VBM的位置上升，从而导致了带隙的变窄，出现了红移现象. 此外，Cd掺杂会使晶胞发生膨胀，这种张应变也是导致Cd

First-principles study of electronic structure for Cd-doped wurtzite ZnO

Using the density-functional theory (DFT) combined with the projector augumented wave (PAW) method, we have investigated the electronic structure of Cd-doped wurtzite ZnO. Analysis of the band structures, density of states (DOS) and partial density of states (PDOS) of Cd_xZn_1-xO shows that the valence band maximum (VBM) is determined by O-2p states and the conduction band minimum (CBM) is occupied by the hybrid Cd-5s and Zn-4s orbital. The energy of CBM decreases and the energy of VBM increases with increasing Cd-doped concentrations. Both effects lead to narrowing of the band gap. Furthermore, it was found that Cd-doped can cause tensile strain in the crystal structure, which also reduces the band gap.