Graphene/MoXY Heterostructures Adjusted by Interlayer Distance, External Electric Field, and Strain for Tunable Devices

Graphene has shown great promise in many electronic devices and systems since it was discovered. However, doping control limits its use in devices. For addressing this problem, graphene/MoXY (X/Y = S, Se, Te and X ≠ Y) heterostructures have been investigated in this work. We analyze electronic and optical properties of the graphene/MoXY heterostructures under various effects such as interlayer distance, external electric field, and mechanical strain by the first-principles method. We find that interlayer distance and external electric field are two prominent parameters to induce tunable homogeneous doping of graphene (G). Compared with interlayer distance modulation, the tuning range of the carrier density in the graphene layer by the external electric field is wider. In the graphene/MoXY heterostructures, the highest carrier density of graphene is simulated to be 4.62 × 1013/cm2 for the G/TeMoS stacking under the electric field strength of 1.0 V/Å. The doping concentration of the graphene layer can be tuned from 3.94 × 1013/cm2 (hole) to 2.00 × 1013/cm2 (electron) subject to the external electric fields of −1.0 and 1.0 V/Å for the G/SMoTe type. In addition, the optical absorption coefficient of the heterostructure graphene/MoSSe is higher than 105/cm in the wavelength range from 550 to 800 nm. The results indicate that these graphene/MoXY heterostructures will have great applications in tunable nanoelectronic devices.