Sub-Millimeter-Scale Monolayer p-Type H-Phase VS2

2D H-phase vanadium disulfide (VS2) is expected to exhibit tunable semiconductor properties as compared with its metallic T-phase structure, and thus is of promise for future electronic applications. However, to date such 2D H-phase VS2 nanostructures have not been realized in experiment likely due to the polymorphs of vanadium sulfides and thermodynamic instability of H-phase VS2. Preparation of H-phase VS2 monolayer with lateral size up to 250 mu m, as a new member in the 2D transition metal dichalcogenides (TMDs) family, is reported. A unique growth environment is built by introducing the molten salt-mediated precursor system as well as the epitaxial mica growth platform, which successfully overcomes the aforementioned growth challenges and enables the evolution of 2D H-phase structure of VS2. The honeycomb-like structure of H-phase VS2 with broken inversion symmetry is confirmed by spherical aberration-corrected scanning transmission electron microscopy and second harmonic generation characterization. The phase structure is found to be ultra-stable up to 500 K. The field-effect device study further demonstrates the p-type semiconducting nature of the 2D H-phase VS2. The study introduces a new phase-stable 2D TMDs materials with potential features for future electronic devices.