Structural, electronic, and transport properties of Janus XMoSiP2 ( S, Se, Te) monolayers: a first-principles study

Abstract

Based on density functional theory calculation, herein we propose XMoSiP2 ( S, Se, Te) monolayers for new two-dimensional (2D) Janus materials. Their crystal structures with dynamical, mechanical, and thermal stabilities, electronic and transport properties are systematically investigated. The results reveal that all three XMoSiP2 monolayers exhibit isotropic elastic properties with high Young’s modulus and negative cohesive energy values, as well as the elastic constants follow the Born-Huang’s criteria, demonstrating their mechanical stability and suggesting the high ability for the experimental synthesis of these materials. From the Perdew–Burke–Ernzerhof functional, the SMoSiP2 is observed as a semiconductor with an indirect bandgap of 1.01 eV, while the SeMoSiP2 and TeMoSiP2 monolayers are observed as direct semiconductors with the bandgap energy of 1.09 and 1.12 eV, respectively. Notably, the bandgap energy of the materials is changed significantly by applying the biaxial strain, and the transition between direct and indirect semiconductors is observed. For the transport ability of the materials, the carrier mobilities are found to be anisotropic for both electron and hole in our studied materials. These findings further highlight the extraordinary properties of the 2D Janus XMoSiP2 materials and their promise for application in electronic devices.