Auger neutralization can explain secondary electron emission (SEE) caused by the impact of Ne$^+$ and Xe$^+$ ions on MgO films. MgO is one of the transparent insulators studied in areas such as plasma display panels (PDPs). The defect level in MgO plays a significant role in improving the SEE. In a previous work, the electronic structures of Ti-doped, Cr-doped, Fe-doped, Ni-doped and Zn-doped MgO were investigated. In this work, the defect states of Zr-doped, Ru-doped, Si-doped and Ge-doped MgO were calculated with CASTEP, which uses a first-principles method. Zr and Ru are elements in the columns adjacent to Ti and Fe in the periodic table, respectively. The occupied defect levels of Zr-doped, Ru-doped, Si-doped and Ge-doped MgO are at 5.19, 2.54, 2.79 and 2.18 eV in the band gap, respectively. If a larger SEE is to be obtained, a higher-energy defect state is more beneficial. The reduced firing voltage of Zr-doped MgO in PDPs, which means a high SEE yield, can be explained by the high-energy defect state of Zr-doped MgO.


Density of states, Defect states, MgO, Auger neutralization, First-principles method