Structural features and electronic properties of Group-IIIB pnictides nanosheets and nanoribbons

Two-dimensional (2D) materials exhibit unique electronic properties compared with their bulks. A systematical study of new type 2D tetragonal materials of MPn (M = Sc and Y; Pn = P, As and Sb) nanosheets and the corresponding nanoribbons are proposed by density functional theory calculations. Several thermodynamically stable 2D tetragonal structures were firstly determined, and such novel tetragonal structures bilayer MPn(100) exhibit extraordinary Weyl semimetal electronic structures, while monolayer MPn(110) are semiconductors. Moreover, bilayer MPn(100) nanoribbons with zigzag edges show metallic behavior, whereas those with linear edges show semiconducting properties. The band gaps for bilayer MPn(100) nanoribbons with linear edges can be significantly tuned by their widths. The zero-gap semiconducting behaviors of 2D tetragonal MPn nanosheets and the tunable band gaps of 1D MPn nanoribbons provide these MPn nanosheets and nanoribbons with promising applications in nanoscale electronic devices.