Remote epitaxy (RE), substrate polarity can "penetrate" two-dimensional materials (2DMs) and act on the epi-layer, showing a prospective universal growth strategy. However, essentially, the role that 2DMs plays in RE has not been deeply investigated so far. Here, the RE of single-crystal films on the weakest polarity/iconicity substrate is realized to reveal its essence physical properties. Graphene facilitates attenuative charge transfer (ACT) from a substrate to epi-layer to construct remote interactions. Interfacial atoms are assembled into "incommensurate" epitaxial relationships through graphene to reduce misfit dislocations in the epilayer. Moreover, graphene reduces the atomic migration barrier, leading to a tendency toward a "layer-by-layer" growth mode. Such film growth mode is different with the conventional epitaxy (CE), and it is beneficial for the fast growth of epi-layers and the reduction of dislocations at coalescence boundaries. The insightful revelation of the role of graphene reveals the interface physics of RE and provides a more valuable guide to using 2DMs to expand three-dimensional materials (3DMs) for application in devices.

Remote epitaxy is a very promising technique for the preparation of single-crystal thin films of flexibly transferred III–V group semiconductors. However, the epilayer nucleation mechanism of remote epitaxy and the epilayer–substrate interface interactions on both sides of graphene are not well-understood. In this study, remote homo- and heteroepitaxy of GaN nucleation layers (NLs) were performed by metal organic chemical vapor deposition on GaN, sapphire (Al2O3), and AlN substrates with transferred single-layer graphene, respectively. The results show that the interface damage of SLG/GaN at high temperature is difficult for us to achieve the remote homoepitaxy of GaN. Therefore, we explored the nucleation mechanism of remote heteroepitaxy of GaN on SLG/Al2O3 and SLG/AlN substrates. Nucleation density, surface coverage, diffusion coefficient, and scaled nucleation density were used to quantify the differences in nucleation information of GaN grown on different polar substrates. Using high-resolution X-ray diffraction and high-resolution transmission electron microscopy analysis, we revealed the interfacial orientation relationship and atomic arrangement distribution between the GaN NLs and substrates on both sides of the SLG. The electrostatic potential effect and adsorption ability of the substrates were further investigated by first-principles calculations based on density functional theory, revealing the principle that the substrate polarity affects the atomic nucleation density. The partial density of states shows that there is long-range orbital hybridization of the electronic states of the substrate and adsorbed atoms in remote epitaxy, and the crystal properties of the substrate play an important role in the in-plane orientation relationship of the NL and substrate across the SLG. The abovementioned results reveal the nature of remote epitaxy and broaden the perspective for the rapid and large-area preparation of single-crystal GaN films.