MoS 2 -OH Bilayer-Mediated Growth of Inch-Sized Monolayer MoS 2 on Arbitrary Substrates.

Due to remarkable electronic property, optical transparency, and mechanical flexibility, monolayer molybdenum disulfide (MoS ₂ ) has been demonstrated to be promising for electronic and optoelectronic devices. To date, the growth of high-quality and large-scale monolayer MoS ₂ has been one of the main challenges for practical applications. Here we present a MoS ₂ -OH bilayer-mediated method that can fabricate inch-sized monolayer MoS ₂ on arbitrary substrates. This approach relies on a layer of hydroxide groups (-OH) that are preferentially attached to the (001) surface of MoS ₂ to form a MoS ₂ -OH bilayer structure for growth of large-area monolayer MoS ₂ during the growth process. Specifically, the hydroxide layer impedes vertical growth of MoS ₂ layers along the [001] zone axis, promoting the monolayer growth of MoS ₂ , constrains growth of the MoS ₂ 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 MoS ₂ from interface oxidation in air, rendering high-quality MoS ₂ monolayers with carrier mobility up to ∼30 cm ² V ^-1 s ^-1 . Using this approach, inch-sized uniform monolayer MoS ₂ has been fabricated on the sapphire and mica and high-quality monolayer MoS ₂ of single-crystalline domains exceeding 200 μm has been grown on various substrates including amorphous SiO ₂ and quartz and crystalline Si, SiC, Si ₃ N ₄ , and graphene This method provides a new opportunity for the monolayer growth of other two-dimensional transition metal dichalcogenides such as WS ₂ and MoSe ₂ .