Optimizing Gold‐Assisted Exfoliation of Layered Transition Metal Dichalcogenides with (3‐Aminopropyl)triethoxysilane (APTES): A Promising Approach for Large‐Area Monolayers

Two-dimensional transition metal dichalcogenides (2D TMDCs) have gained significant attention from the scientific community due to their exceptional properties. Recently, the metal-assisted exfoliation technique has emerged as a promising method for producing large-area, high-quality 2D monolayers. However, achieving strong adhesion between metal foil and substrate during the exfoliation process remains a major challenge, preventing successful exfoliation. To overcome this issue, this study explores the application of (3-Aminopropyl)triethoxysilane (APTES) as an adhesion layer to substantially improve adhesion between the monolayers and hydrophilic substrates such as SiO2, allowing for a high yield of mm-sized monolayers. Two sample sets, obtained from the same MoS2 crystal via gold-assisted exfoliation with APTES-treated substrates and from standard scotch tape exfoliation, are statistically compared. APTES significantly improves exfoliation performance, yielding larger monolayers compared to conventional methods. This improvement enables the effective exfoliation with the gold-tape method, which otherwise results in no yield. Through Raman and photoluminescence characterization techniques, it is found that the flakes obtained from gold-assisted exfoliation and APTES are comparable to those obtained by standard scotch-tape exfoliation in terms of defects and optical properties, showing signatures of strain-induced Raman shift and n-type doping.