Wide band gap monolayer metal oxychlorides: a first-principles prediction

Based on first-principles calculations, we systematically investigated the stability, interlayer interactions, and electronic and optical properties of new two-dimensional (2D) metal oxychlorides MOCl (M = Ga, Y, and Al). We found that the MOCl family exhibits high stability, easy exfoliation, and wide band gaps. Moreover, the dielectric constants of GaOCl and AlOCl exhibit in-plane anisotropy due to their asymmetric structures. In contrast, the monolayer YOCl possesses a high and isotropic dielectric constant, suggesting its potential application as a dielectric layer in electronics. Furthermore, the Raman spectra of MOCl monolayers were calculated. The Raman signatures of each MOCl compound are provided to facilitate experimental characterization. These fascinating properties render monolayer MOCl a promising candidate for ultrathin solar-blind ultraviolet electronic devices and dielectric layers.