Study of point defect on the stability and magneto-optical properties of ZnO:Cu by first-principles

ABSTRACT

The magnetic and optical properties of Cu-doped ZnO systems have been widely studied in experimental, but the magnetic sources of the coexistence of Cu replacing Zn and the O vacancy systems are controversial. First-principles can compensate for the experimental deficiencies. The effects of Cu-doping and point defects on the magnetic and optical properties of ZnO were studied using geometry optimisation and energy calculation based on first-principle generalised gradient approximation?+?U method of the density functional theory. Results indicate that the band gaps and absorption spectra of Zn₁₅CuO₁₆, Zn₁₄CuO₁₆, and Zn₁₅Cu_iO₁₆ systems become narrowed and red-shifted, respectively, compared with those of pure ZnO. In addition, the system with Cu replaces Zn, and Zn vacancy coexists in ZnO. The doping system has the relatively largest magnetic moment and can achieve a ferromagnetic long-range order, and the Curie temperature can reach room temperature. As an electron injection source, this system can reach 100% electron spin-polarisation and exhibit half-metallic properties, which are relatively favourable for dilute magnetic semiconductor (DMS). Therefore, this system has certain theoretical reference value in the design and preparation of light-emitting devices or DMS.