Spin-orbit coupling tunable electronic properties of 1T ′-MoS2 and ternary Janus 1T ′-MoSSe monolayers: Theoretical prediction

MoS 2 can exist in many different polytypes, such as trigonal prismatic, distorted octahedral, or octahedral. The 2 H-phase of MoS 2 has been extensively studied in recent times, but there are very few studies focusing on the remaining phases, especially the distorted octahedral T ' )-phase. Here, we design the MoS 2 monolayer and Janus MoSSe structure in the 1 T ' phase and study their electronic properties within the framework of firstprinciples calculations. Both 1 T ' -MoS 2 and 1 T ' -MoSSe monolayers are confirmed to have structural stability and anisotropic mechanical characteristics. Interestingly, while the 1 T ' -MoS 2 monolayer exhibits metallic characteristics, Janus MoSSe in the 1 T ' phase is a semiconductor with a small band gap of 0.04 eV. More interestingly, a tiny bandgap of 0.05 eV has opened up in the 1 T ' -MoS 2 monolayer due to the spin-orbit coupling effect. We also study the mobility of carriers in the semiconductor Janus 1 T ' -MoSSe monolayer. 1 T ' -MoSSe monolayer exhibits a high anisotropic carrier mobility due to its high anisotropic crystal structure. Surprisingly, 1 T ' -MoSSe monolayer possesses extremely high electron mobility, up to 4 . 58 x 10 3 cm 2 V -1 s -1 . Our findings give a deeper insight into the 1 T ' -phase of transition metal dichalcogenide and its Janus structure.