Electronic structure and optical properties of Cu-doped SnO2

Abstract

The SnO2 diluted magnetic semiconductors formed by doping with transition metals have great potential in making large scale integrated circuits for the great photoelectric applications. In this article, based on the spin polarized density functional theory (DFT), the geometric structures, the lattice parameters, electronic structures and optical properties of pure and Cu-doped SnO2 are investigated. The lattice parameters and electronic properties of 4.17 wt.% and 6.25 wt.% concentration Cu-doped SnO2 have no tremendous change. While, the total energy decreases with the increasing of Cu concentration, which indicates that the structure stability enhances after Cu doping. At the same time, the O atoms are attracted by Cu atom, and the bond length of Cu-O becomes short. The band gap gradually reduces with the increasing of Cu concentration, and the Fermi energy level shifts towards valence band. For Cu-doped SnO2, the spin up and spin down energy levels are asymmetrical, and the former is much more than the latter one, which indicates that Cu-doped SnO2 has half-metallic behavior. Moreover, the spin-orbit coupling appears near the Fermi level, which shows hybrid effects between Cu 3d and O 2p states. In addition, the absorption edge of SnO2 has a red shift, and the absorption intensity enhances, which indicates that the absorption ability in visible light range increases after Cu doping. For the ultraviolet light region, the absorption peak is maximum, while the peak value decreases with the increasing of Cu concentration. The theoretical calculation results show that Cu-doped SnO2 has a good potential for photoelectric applications.