Electronic structure and optical properties of ZnO doped with carbon

Electronic structure and optical properties of ZnO doped with carbon have been investigated by using density functional theory based on first-principles ultrasoft pseudopotential method. The calculated results show that there is a significant difference in electronic structures between the cases of C substituting O and C substituting Zn in ZnO Which is caused by both the electronic structure of C atom and its interaction with the neighboring atoms. We also find that the optical properties are charged in the low-energy region after doping, while in the high-energy region the optical properties are almost not influenced by doping with C. The changes of optical properties are qualitatively explained in connection with the calculated electronic structure.