First principle investigations of the structural, electronic, and phase stability of layered, quasi-2D ZnSb

Recently, the two-dimensional (2D) materials have become potential candidates for various technological applications in spintronics and optoelectronics soon after the discovery of graphene from the mechanical exfoliation of graphite. In the present study, the structural, electronic, and phase stability of layered quasi-2D ZnSb compounds have been tuned using the first principle calculations based on density functional theory (DFT). We invoked the Perdew-Burke-Ernzerhof (PBE) functional and the projected augmented wave (PAW) method during all the calculations. Based on our numerical results, the novel tetragonal phase of 2D-ZnSb is the most stable phase among the quasi-2D structures. We reported the pressure-induced phase transition between orthorhombic 3D-ZnSb to tetragonal 2D-ZnSb at 12.48 GPa/atom. The projected density of states indicates the strong p-d hybridization between Sb-5p and Zn-3d states confirming the nature of strong covalent bonding between them. We predicted the possibility of the monolayer in tetragonal 2D-ZnSb and orthorhombic 3D-ZnSb according to the exfoliation energy criterion. The electronic band structures suggest the metallic characteristics of all the quasi-2D structures. In addition, the monolayer of 3D-ZnSb has been predicted to be dynamically stable as manifested in phonon dispersion bands. Surprisingly, the semiconducting bandgap nature of orthorhombic 3D-ZnSb changes from indirect and narrow to direct and sizable while going from 3D bulk to 2D monolayer. Further, we estimated the value of work functions for the surface of t-ZnSb (quasi-2D) and o-ZnSb (3D) as 4.61 eV and 4.04 eV respectively. Such materials can find niche applications in next-generation electronic devices utilizing 2D heterostructures.