Large-Area Transfer of 2D TMDCs Assisted by Water-soluble layer for Potential Device Applications

Abstract: Layer transfer offers enormous potential for the industrial implementation of 2D material technology platforms. However, the transfer method used must retain as-grown uniformity and cleanliness in the transferred films for the fabrication of 2D material-based. Additionally, the method used must be capable of large-area transfer to maintain wafer-scale fabrication standards. Here, a facile route to transfer centimeter-scale synthesized 2D TMDCs (3L MoS2, 1L WS2) onto various substrates such as sapphire, SiO2/Si, and flexible substrates (mica, polyimide) has been developed using a water-soluble layer (Na2S/Na2SO4) underneath the as-grown film. The developed transfer process represents a fast, clean, generic, and scalable technique to transfer 2D atomic layers. The key strategy used in this process includes the dissolution of Na2S/Na2SO4 layer due to the penetration of NaOH solution between the growth substrate and hydrophobic 2D TMDC film. As a proof-of-concept device, a broadband photodetector has been fabricated onto transferred 3L MoS2, which shows photoresponse behavior for a wide range of wavelength ranging from NIR to UV. The enhancement in photocurrent was found to be 100 times and 10 times to dark current in the UV and visible region, respectively. This work opens up the pathway towards flexible electronics and optoelectronics.