title: Surface-energy-assisted perfect transfer of centimeter-scale monolayer and few-layer MoS₂ films onto arbitrary substrates.
abstract: The transfer of synthesized 2D MoS2 films is important for fundamental and applied research. However, it is problematic to translate the well-established transfer processes for graphene to MoS2 due to different growth mechanisms and surface properties. Here we demonstrate a surface-energy-assisted process that can perfectly transfer centimeter-scale monolayer and few-layer MoS2 films from original growth substrates onto arbitrary substrates with no observable wrinkles, cracks, and polymer residues. The unique strategies used in this process include leveraging the penetration of water between hydrophobic MoS2 films and hydrophilic growth substrates to lift off the films and dry transferring the film after the lift off. This is in stark contrast with the previous transfer process for synthesized MoS2 films, which explores the etching of the growth substrate by hot base solutions to lift off the films. Our transfer process can effectively eliminate the mechanical force caused by bubble generations, the attacks from chemical etchants, and the capillary force induced when transferring the film outside solutions as in the previous transfer process, which consists of the major causes for the previous unsatisfactory transfer. Our transfer process also benefits from using polystyrene (PS), instead of poly(methyl methacrylate) (PMMA) that was widely used previously, as the carrier polymer. PS can form more intimate interaction with MoS2 films than PMMA and is important for maintaining the integrity of the film during the transfer process. This surface-energy-assisted approach can be generally applied to the transfer of other 2D materials, such as WS2.
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Fiber and Polymer Science, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Alper
authors.initials: A
authors.lastname: Gurarslan
authors.forename: Yifei
authors.initials: Y
authors.lastname: Yu
authors.forename: Liqin
authors.initials: L
authors.lastname: Su
authors.forename: Yiling
authors.initials: Y
authors.lastname: Yu
authors.forename: Francisco
authors.initials: F
authors.lastname: Suarez
authors.forename: Shanshan
authors.initials: S
authors.lastname: Yao
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhu
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ozturk
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Linyou
authors.initials: L
authors.lastname: Cao
keywords: 2D materials; large scale; molybdenum disulfide; surface energy; tungsten disulfide