Wafer-Scale Growth of Pristine and Doped Monolayer MoS 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 MoS 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 MoS. This method can be used to prepare substitutionally doped monolayer MoS films. By using ReCl as the dopant precursor, we have obtained continuous Re-doped monolayer MoS films on sapphire wafers. Elemental analysis confirms successful Re-doping of the MoS film. Spherical aberration-corrected scanning transmission electron microscopy characterization reveals that the Re atoms are incorporated at the substitutional Mo sites in the MoS lattice. The incorporation of Re atoms leads to n-type doping of MoS as evidenced by Kelvin probe force microscope studies. Electrical measurements reveal that the transport properties of the Re-doped monolayer MoS is dramatically enhanced as compared with the pristine MoS. 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.