Fig. 2

a. Schematics of epitaxial lift-off techniques using a chemically etched sacrificial layer, b. An optically induced separation between the epilayer and substrate, c. Brule-force mechanical spalling using a metal stressor layer, d. 2D material assisted layer transfer [64], e. Schematic illustration explaining the 2DLT and recycling substrate, f. Atomic force microscopy (AFM) image of the surface of the GaN grown on the graphene buffer layer. The RMS roughness is 0.18 nm, g. Photograph of the three-times-reused substrate and the exfoliated GaN epilayers [67], h. Schematic of successive multiple membranes production by 2DLT and wafer recycling, i. Photographs of exfoliated membrane surface (top) and EBSD map (bottom) [68], j. X-ray rocking curves of AlN grown on sapphire (black line) and plasma treated-graphene/sapphire substrates (red line), k. Atomically resolved STEM image of the interface of AlN/graphene/sapphire [72], l. Strain-relaxation efficiency of InGaP grown on graphene/GaAs and on GaAs [73], m. Schematic diagram of strain relaxation via the dislocation, the T indicates where a dislocation forma, and the schematic diagram below is strain via spontaneous relaxation, n. Cross-sectional view of GaP grown on bare GaAs, o. Cross-sectional view of GaP grown on graphene/GaAs [58]