Structural, electronic, and transport properties of Janus GaInX 2 (X = S, Se, Te) monolayers: first-principles study

Abstract

Two-dimensional Janus monolayers have outstanding electronic and transport properties due to their asymmetric atomic structures. In the present work, we systematically study the structural, electronic, and transport properties of the Janus GaInX 2 (X = S, Se, Te) monolayers by using the first-principles calculations. The stability of the investigated monolayers is confirmed via the analysis of vibrational spectrum and molecular dynamics simulations. Our calculations demonstrate that while GaInS2 and GaInSe2 monolayers are direct semiconductors, GaInTe2 monolayer exhibits the characteristics of an indirect semiconductor. The band gap of GaInX 2 decreases when the chalcogen element X varies from S to Te. Obtained results reveal that small spin–orbit splitting energy in the valence band is found around the Γ point of the Brillouin zone when the spin–orbit coupling is included. Interestingly, GaInS2 and GaInSe2 have high and directional isotropic electron mobility meanwhile the directional anisotropy of the electron mobility is found in the Janus GaInTe2 monolayer. Our findings not only present superior physical properties of GaInX 2 monolayers but also show promising potential applications of these materials in nanoelectronic devices.