Optical identification of point defects in monolayer beryllium oxide by ab initio calculations

Abstract

Triggered by recent experimental observation of monolayer (1L) beryllium oxide (BeO), we systematically investigate the formation energies, thermodynamic stabilities and optoelectronic properties of point defects in 1L BeO by the hybrid density functional calculations and ab initio molecular dynamics simulations. Under Be rich(poor) condition, we find that the most favorable vacancy and antisite defects are respectively the VO(VBe) and the OBe(BeO). Most of these defects are found to be thermodynamically stable at room temperature. The VBe and VO show strong attractive interaction, which tends to result in a cooperative effect. Moreover, we reveal the magnetism and the tunable optoelectronic properties induced by these defects. Specifically, due to the defect states involved interband transitions, the new characteristic peaks and the improved absorptions with large absorption coefficients (105 cm−1) are demonstrated in the visible and near-UV region, which further help identify the defects. The microscopic understanding about the point defects would provide guidance for experimental design and synthesis of 1L BeO based optoelectronic devices via defect engineering.