Thermodynamically Driven Tilt Grain Boundaries of Monolayer Crystals Using Catalytic Liquid Alloys

Abstract

We report a method to precisely control the atomic defects at grain boundaries (GBs) of monolayer MoS 2 by vapor−liquid−solid (VLS) growth using sodium molybdate liquid alloys, which serve as growth catalysts to guide the formations of the thermodynamically most stable GB structure. The Mo-rich chemical environment of the alloys results in Mopolar 5|7 defects with a yield exceeding 95%. The photoluminescence (PL) intensity of VLS-grown polycrystalline MoS 2 films markedly exceeds that of the films, exhibiting abundant S 5|7 defects, which are kinetically driven by vapor−solid−solid growths. Density functional theory calculations indicate that the enhanced PL intensity is due to the suppression of nonradiative recombination of charged excitons with donor-type defects of adsorbed Na elements on S 5|7 defects. Catalytic liquid alloys can aid in determining a type of atomic defect even in various polycrystalline 2D films, which accordingly provides a technical clue to engineer their properties.

High-throughput dry transfer and excitonic properties of twisted bilayers based on CVD-grown transition metal dichalcogenides

“…40,41 It should be noted that the exact edge configurations including the edge reconstruction and the step edge cannot be identified simply from the grain shape alone. 42–44 These individual crystals are oriented in random directions owing to the non-epitaxial growth on the amorphous SiO 2 surface. First, the large WS 2 crystal was lifted with a stamp.…”

Two-dimensional materials for future information technology: status and prospects

“…GB is another type of 1D defect in 2D materials, separating two grains whose lattices are tilted relative to each other by a misorientation angle, which is frequently observed in CVD grown samples [199][200][201][202][203]. The atomic structure of GB varies with the misorientation angle.…”