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 SnO_2, 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.

Keywords:

• SnO2
• Cu-doped
• density functional theory
• electronic structure
• optical properties

Additional information

Funding

The project was supported by the National Natural Science Fund of China (61664008), the Special Research Funds for Discipline Construction of High Level University Project (2015SXTS02), the Scientific and Technological Innovation Team (2017CXTD-01), the project of production, learning and research cooperation (2017cxy05) and the College Training Program of Innovation and Entrepreneurship of Shaanxi Province (201813024).