Wafer-Scale Growth of Pristine and Doped Monolayer MoS₂ Films for Electronic Device Applications

Scalable production and controlled doping of large-area two-dimensional transition-metal dichalcogenide films are fundamental steps toward their applications in electronic devices. Although a variety of methods for preparation of wafer-scale transition-metal dichalcogenide films have been developed, it is still challenging to realize homogeneous doping of the large-area films to modulate their electronic properties. In this paper, we report a new chemical vapor deposition (CVD) method for preparation of wafer-scale pristine and doped monolayer MoS₂ films on 2-inch sapphire wafers. The molybdenum precursors are supplied in a "face-to-face" manner from a silica gel plate to the sapphire wafer, which guarantees uniform nucleation and growth of monolayer MoS₂. This method can be used to prepare substitutionally doped monolayer MoS₂ films. By using ReCl₃ as the dopant precursor, we have obtained continuous Re-doped monolayer MoS₂ films on sapphire wafers. Elemental analysis confirms successful Re-doping of the MoS₂ film. Spherical aberration-corrected scanning transmission electron microscopy characterization reveals that the Re atoms are incorporated at the substitutional Mo sites in the MoS₂ lattice. The incorporation of Re atoms leads to n-type doping of MoS₂ as evidenced by Kelvin probe force microscope studies. Electrical measurements reveal that the transport properties of the Re-doped monolayer MoS₂ is dramatically enhanced as compared with the pristine MoS₂. The CVD method developed in this study can be applied to the production of a variety of two-dimensional transition-metal dichalcogenide films suitable for applications in electronic devices.