Optical Identification of Topological Defect Types in Monolayer Arsenene by First-Principles Calculation

Recent theoretical research has demonstrated that a new two-dimensional material, the monolayer of gray arsenic (arsenene), can respond to the blue and ultraviolet light leading to possible optoelectronic applications. However, some topological defects often affect various properties of arsenene. Here we theoretically investigate the arsenene with monovacancy (MV), divacancy (DV), and Stone-Wales (SW) defects. Three kinds of MVs are identified and the reconstructed structures of DV and SW defects are confirmed. The dynamical stability, rearrangement, and migration for these defects are investigated in detail. Optical spectral calculations indicate that the MVs enhance optical transitions in the forbidden bands of arsenene and two new characteristic peaks appear in the dielectric and absorption spectra. However, there is only one new peak in the spectrum induced by DV and SW defects. Calculations of band structures indicate that the MV induces two defect bands in the forbidden bands of pristine arsenene, which are responsible for the two new peaks in the dielectric and absorption spectra. Our findings suggest that the optical dielectric and absorption spectra can help identify the types of topological defects in arsenene.