MoS₂-OH Bilayer-Mediated Growth of Inch-Sized Monolayer MoS₂ on Arbitrary Substrates

Due to remarkable electronic property, optical transparency, and mechanical flexibility, monolayer molybdenum disulfide (MoS₂) has been demonstrated to be promising for electronic and optoelectronic devices. To date, the growth of high-quality and large-scale monolayer MoS₂ has been one of the main challenges for practical applications. Here we present a MoS₂-OH bilayer-mediated method that can fabricate inch-sized monolayer MoS₂ on arbitrary substrates. This approach relies on a layer of hydroxide groups (-OH) that are preferentially attached to the (001) surface of MoS₂ to form a MoS₂-OH bilayer structure for growth of large-area monolayer MoS₂ during the growth process. Specifically, the hydroxide layer impedes vertical growth of MoS₂ layers along the [001] zone axis, promoting the monolayer growth of MoS₂, constrains growth of the MoS₂ monolayer only in the lateral direction into larger area, and effectively reduces sulfur vacancies and defects according to density functional theory calculations. Finally, the hydroxide groups advantageously prevent the MoS₂ from interface oxidation in air, rendering high-quality MoS₂ monolayers with carrier mobility up to ∼30 cm² V^-1 s^-1. Using this approach, inch-sized uniform monolayer MoS₂ has been fabricated on the sapphire and mica and high-quality monolayer MoS₂ of single-crystalline domains exceeding 200 μm has been grown on various substrates including amorphous SiO₂ and quartz and crystalline Si, SiC, Si₃N₄, and graphene This method provides a new opportunity for the monolayer growth of other two-dimensional transition metal dichalcogenides such as WS₂ and MoSe₂.