Quasiparticle band structures and optical properties of monolayer ZrNX (X=Cl, Br, I) under exciton effect

Abstract

The quasiparticle band structures of monolayer α-ZrNX (X = Cl, Br, I) and β-ZrNX (X = Cl, Br, I) are researched by using an exact quasiparticle approximation GW theory. Our results show that both monolayer α-ZrNX (X = Cl, Br, I) and β-ZrNX (X = Cl, Br, I) are two-dimensional semiconductors with wide band gaps (larger than 3.5 eV). We have considered the effect of exciton, calculated their optical properties by GW0+BSE method, and obtained the accurate dielectric function spectrum. We find that monolayer α-ZrNI has excellent light absorption in the ultraviolet region. By studying the exciton binding energy of monolayer α-ZrNX (X = Cl, Br, I), it is found that monolayer α-ZrNCl and α-ZrNBr have relatively large exciton binding energies (0.74 eV, 0.67 eV). The relationship between the band gaps and the exciton binding energies in two-dimensional semiconductors has also been discussed. Our present work gives more accurate information on the energy band structures and optical properties of monolayer ZrNX (X = Cl, Br, I), which is of guiding significance for the future investigation on monolayer ZrNX (X = Cl, Br, I). And the investigation of the exciton binding energy has a reference value for the study of the exciton effect in two-dimensional semiconductors.