Atomically Thin Group V Elemental Films: Theoretical Investigations of Antimonene Allotropes

Group V elemental monolayers including phosphorene are emerging as promising 2D materials with semiconducting electronic properties. Here, we present the results of first-principles calculations on stability, mechanical and electronic properties of 2D antimony (Sb), antimonene. Our calculations show that free-standing alpha and beta allotropes of antimonene are stable and semiconducting. The a-Sb has a puckered structure with two atomic sublayers and beta-Sb has a buckled hexagonal lattice. The calculated Raman spectra and STM images have distinct features thus facilitating characterization of both allotropes. The beta-Sb has nearly isotropic mechanical properties, whereas alpha-Sb shows strongly anisotropic characteristics. An indirect-direct band gap transition is expected with moderate tensile strains applied to the monolayers, which opens up the possibility of their applications in optoelectronics.