Surface-Functionalization-Mediated Direct Transfer of Molybdenum Disulfide for Large-Area Flexible Devices

The transfer of synthesized large-area 2D materials to arbitrary substrates is expected to be a vital step for the development of flexible device fabrication processes. The currently used hazardous acid-based wet chemical etching process for transferring large-area MoS₂ films is deemed to be unsuitable because it significantly degrades the material and damages growth substrates. Surface energy-assisted water-based transfer processes do not require corrosive chemicals during the transfer process; however, the concept is not investigated at the wafer scale due to a lack of both optimization and in-depth understanding. In this study, a wafer-scale water-assisted transfer process for metal–organic chemical vapor-deposited MoS₂ films based on the hydrofluoric acid treatment of a SiO₂ surface before the growth is demonstrated. Such surface treatment enhances the strongly adhering silanol groups, which allows the direct transfer of large-area, continuous, and defect-free MoS₂ films; it also facilitates the reuse of growth substrate. The developed transfer method allows direct fabrication of flexible devices without the need for a polymeric supporting layer. It is believed that the proposed method can be an alternative defect- and residue-free transfer method for the development of MoS₂-based next-generation flexible devices.