Twisted bilayer graphene (tBLG) has recently attracted growing interest due to its unique twist-angle-dependent electronic properties. The preparation of high-quality large-area bilayer graphene with rich rotation angles would be important for the investigation of angle-dependent physics and applications, which, however, is still challenging. Here, we demonstrate a chemical vapor deposition (CVD) approach for growing high-quality tBLG using a hetero-site nucleation strategy, which enables the nucleation of the second layer at a different site from that of the first layer. The fraction of tBLGs in bilayer graphene domains with twist angles ranging from 0° to 30° was found to be improved to 88%, which is significantly higher than those reported previously. The hetero-site nucleation behavior was carefully investigated using an isotope-labeling technique. Furthermore, the clear Moiré patterns and ultrahigh room-temperature carrier mobility of 68,000 cm2 V−1 s−1 confirmed the high crystalline quality of our tBLG. Our study opens an avenue for the controllable growth of tBLGs for both fundamental research and practical applications.
The rich and complex arrangements of metal atoms in high‐index metal facets afford appealing physical and chemical properties, which attracts extensive research interest in material science for the applications in catalysis and surface chemistry. However, it is still a challenge to prepare large‐area high‐index single crystals in a controllable and cost‐efficient manner. Herein, entire commercially available decimeter‐sized polycrystalline Cu foils are successfully transformed into single crystals with a series of high‐index facets, relying on a strain‐engineered anomalous grain growth technique. The introduction of a moderate thermal‐contact stress upon the Cu foil during the annealing leads to the formation of high‐index grains dominated by the thermal strain of the Cu foils, rather than the (111) surface driven by the surface energy. Besides, the designed static gradient of the temperature enables the as‐formed high‐index grain seed to expand throughout the entire Cu foil. The as‐received high‐index Cu foils can serve as the templates for producing high‐index single‐crystal Cu‐based alloys. This work provides an appealing material basis for the epitaxial growth of 2D materials, and the applications that require the unique surface structures of high‐index metal foils and their alloys.
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