Synthesis of large area and high quality MoS₂ on Au(111) monolayers with single domain orientation

The employment of transition metal dichalcogenides, and in particular single layer (SL) MoS₂ for electronic devices, demands for a controllable growth of highly crystalline layers featuring large area with a low concentration of defects to preserve their outstanding electronic properties. Moreover, thanks to the peculiar electronic structure, new degrees of freedom are accessible allowing for spin- and valley-dependent phenomena, that can be retained in devices only through singly-oriented domains. Current chemical vapor deposition methods have not been able to achieve this and have produced mirror twin domains leading to the formation of domain boundaries and dislocations in the layer.
We present a protocol for the synthesis through physical vapor deposition of SL MoS₂ on Au(111) with a single domain orientation. We demonstrate the structural properties using a combination of surface science techniques, including scanning tunneling microscopy and photoelectron diffraction. Angular resolved photoemission measurements (ARPES) confirmed the single layer character and the high structural quality of MoS₂ while the single domain orientation allowed the measurement, through Spin-resolved ARPES, of the complete spin polarization with spin reversal of the states near K and -K points.