Theoretical design of novel two-dimensional Mo2S2X2 (X=C,Si) and their electronic and mechanical properties

Novel two-dimensional Mo2S2C2 and Mo2S2Si2 are theoretically designed and their stability, electronic and mechanical properties are investigated by using first principles calculations. The absent of imaginary frequencies in phonon dispersion and no atomic bond broken in molecule dynamic simulation well confirm the dynamic and thermal stability of Mo2S2C2 and Mo2S2Si2. Further calculations indicate both Mo2S2C2 and Mo2S2Si2 possess excellent mechanical flexibility, which can sustain the critical strains -22% and 23%, respectively. The calculated electronic band structures based on HSE06 method reveal that Mo2S2C2 and Mo2S2Si2 are zero band gap materials. In addition, they can form p-type contact Mo2S2C2/MoS2 and Mo2S2Si2/MoS2 heterostructures with the schottky barrier height -0.72 eV and 0.62 eV, respectively, which verify they may be potential electrodes for MoS2 based devices.