Toward Scalable Transfer of 2D Semiconductors by Overcoming High Exfoliation Energy

Two-dimensional van der Waals (2D-vdW) materials, such as Tin Selenide (SnSe) offer opportunities for next-generation photonic and electronic devices due to their highly anisotropic properties, tunable bandgap, and strong phonon resonances. However, lifting off and transferring SnSe film onto the desired substrate is critical for developing devices, as the applicability of the high-quality epitaxial growth films is often limited by the lattice match between the film and the grown substrate. This process, however, is particularly challenging due to high exfoliation energy, resulting in small, fractured flakes rather than a large, uniform, and undamaged film. To overcome this long-standing challenge, we introduce a scalable wet-transfer approach to lift off and transfer SnSe thin film grown by MBE. For the first time, we report a novel lift-off technique to peel epitaxial grown SnSe film from a Sapphire substrate using an etchant solution, a polymethyl methacrylate (PMMA) assistant, TRT (thermal release tape). We transferred the clean and intact large area of thin films with different thicknesses to diverse targets. This technique is, therefore, enabling advancing 2D materials from laboratory to practical applications and co-integrated with silicon technology, such as CMOS-integrated photodetectors.