Theoretical Study on Electronic Structure and Conductivity of Y-Doped ZnO

Based on the first principles calculations, using density functional theory within the generalized gradient approximation, we perform a study on Y-doped ZnO, where the total density of states (TDOS), the partial density of states (PDOS) and band structure and conductivity of the systems are included. The calculated results show that with the increase of concentration of Y, the lattice parameter is expanded. Moreover, from the PDOS, we can see that the valence band maximum is determined by the O-p states and the conduction band minimum is depended on the Y-s and Zn-s states. Simultaneously, it is found that as the increase of concentration of Y, the band gap of dopant system is broadening. Its reason is that the valence band moving towards into the lower energy is more than the conduction band. In addition, we calculated the number of the electrons which go into the conduction band. We found that as the increase of doping concentration, the number of the electrons decrease. The conductivity of the system is enhanced with the increase of Y concentration. Therefore, it can be concluded that the low concentration of Y doping ZnO demonstrates the better conductivity.