The manuscript reports that the initial strain relaxation of highly mismatched GaSb layers grown on GaAs (001) is governed by the two-dimensional (2D), periodic interfacial misfit (IMF) dislocation array growth mode. Under optimized growth conditions, only pure 90° dislocations are generated along both [110] and [11¯0] directions that are located at GaSb/GaAs interface, which leads to very low threading dislocation density propagated along the growth direction. The long-range uniformity and subsequent strain relaxation of the 2D and periodic IMF array are demonstrated via transmission electron microscopy and scanning transmission electron microscopy images at GaSb/GaAs interface.
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.
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