Rational Design on Wrinkle-Less Transfer of Transition Metal Dichalcogenide Monolayer by Adjustable Wettability-Assisted Transfer Method

Transfer-induced wrinkles are universal issues when transferring transition metal dichalcogenide (TMDC) monolayer from an as-grown substrate to a target substrate. The undesired transfer-induced wrinkles can mainly be attributed to wettability, which refers to the ability of a liquid to come in contact with a solid surface. Herein, an adjustable wettability-assisted transfer (AWAT) method with different mixtures of transfer media to reduce the density of wrinkles is developed. By manipulating the wettability of the transfer medium with different ratios of alcohol and de-ionized (DI) water, the TMDC monolayer is smoothly attached to the target substrate, thus achieving a wrinkle-less transferred TMDC monolayer. With this method, the density of wrinkles can be decreased by ≈15–20% compared with the conventional transfer method by pure DI water. The transferred MoS₂ monolayer with the AWAT method can achieve enhanced carrier mobility from ≈20 to ≈35 cm² V⁻¹ s⁻¹ in average, which is 30 times larger than that transferred by pure DI water. The AWAT method applied to a WS₂ monolayer onto a SiO₂/p⁺-Si substrate and a MoS₂ monolayer onto a HfO₂/p⁺-Si substrate are demonstrated, which is beneficial in research and applications involving the transfer of TMDC monolayer.