Complicated point defects in monolayer Ga2S3: stability, midgap states and magnetism.

The structural, electronic and magnetic properties of single-layer α-Ga 2 S 3 with intrinsic point defects, including five vacancy defects, three interstitial defects, and five antisite defects, are systematically investigated. [Display omitted] • The point defects properties of single-layer semiconductor α-Ga 2 S 3 are complicated, since there are nonequivalent Ga and S atomic sites. • The stability, midgap states and magnetism of five vacancy defects, three interstitial defects, and five antisite defects are investigated. • The origin of the midgap states and magnetic moments of the defects are also investigated. Motivated by recent experimental realization of single-layer α-Ga 2 S 3 [Zheng et al. , Adv. Funct. Mater. 31, 2008307(2021)], by using first principles calculations, we systematically investigated the structural, electronic and magnetic properties of single-layer α-Ga 2 S 3 with intrinsic point defects. Although it is a binary semiconductor, its point defects properties are complicated, since there are nonequivalent Ga and S atomic sites in this compound. The most energetically stable vacancy and interstitial defect are V S2 and S i1 for the entire sulfur chemical potential range, while the most energetically favorable antisite defect is dependent on the sulfur chemical potential, such as Ga S2 under S-poor condition and S Ga1 (S Ga2) under S-rich condition. The sulfur vacancy defects (V S1 , V S2 and V S2) have induced spin-degenerated defect states in the band gap or the valence band edge, while the gallium vacancy defects (V Ga1, and V Ga2) have spin-polarized defect states in the band gap or valence band edge with the magnetic moment of 1.30 μ B and 1.21μ B per defect. The interstitial defects (Ga i1 , S i1 and S i2) can generate spin-degenerated in-gap defect states. The antisite defects (Ga S1 , Ga S2 , Ga S3 , S Ga1 , and S Ga2) have spin-polarized in-gap defect states with weak magnetic moments of 0.70 μ B , 0.69μ B, 0.64μ B, 0.66μ B and 0.65μ B per defect. Besides, the origin of the defect states and magnetic moments are examined in detail. These findings are helpful for understanding the defect properties of two dimensional III A- VI A binary chalcogenide Ga 2 S 3 and improving its technological applications. [ABSTRACT FROM AUTHOR]