Density functional theory based characterization of point defects in two-dimensional Zn2(V,Nb,Ta)N3 ternary nitrides

Structural defects, including mono- and double- vacancies, commonly presented at the surface of two-dimensional materials (2D), including 2D ternary nitrides. These point defects can alter electronic structure of 2D ternary nitrides. In this work, density functional theory based simulations are utilized for a comprehensive characterization of point defects in Zn₂(V,Nb,Ta)N₃ monolayers. The monovacancies of Z and N in Zn₂(V,Nb,Ta)N₃ monolayers are found to have the lowest formation energy among all studied defects. The presence of the monovacancy of N leads to a blue shift of valance and conduction bands of the Zn₂(V,Nb,Ta)N₃ monolayers and the formation of deep trap states in their fundamental gap in the vicinity of the Fermi level, while the presence of the monovacancy of Zn induces the formation of shallow trap states within the fundamental gap on the Zn₂(V,Nb,Ta)N₃ monolayers. The scanning tunneling microscopy simulated images of point defects in Zn₂(V,Nb,Ta)N₃ monolayers obtained in this work can facilitate the detection of these defects in experiments. Therefore, the theoretical characterization of defects in Zn₂(V,Nb,Ta)N₃ monolayers presented in this work can provide helpful guidance for future experiments.