Technique of exfoliation and transfer based on 2D material-assisted epitaxy and related flexible devices. (A) Schematic of the transfer process based on 2D material. (B) Density functional theory calculation results of plane-averaged electron density of GaAs for As-Ga and As-As interactions [7]. (C) HAADF-STEM image of GaAs grown on patterned graphene/Ge [60]. (D) Transmission electron microscopy image of the heterostructure of CoFe₂O₄/Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ film [58]. (E) Photograph and structure schematic of microrod LED [55]. (F) Image of the fabricated blue LED via van der Waals epitaxy [65]. (G) Photograph of the transferred nitride film on the sapphire substrate using an h-BN buffer layer [5]. (H) Image of flexible GaN HEMT devices [85].