In Situ Growth of High-Quality Single-Crystal Twisted Bilayer Graphene on Liquid Copper

Twisted bilayer graphene (TBG) generates significant attention in the fundamental research of 2D materials due to its distinct twist-angle-dependent properties. Exploring the efficient production of TBG with a wide range of twist angles stands as one of the major frontiers in moire materials. Here, the local space-confined chemical vapor deposition growth technique for high-quality single-crystal TBG with twist angles ranging from 0 degrees to 30 degrees on liquid copper substrates is reported. The clean surface, pristine interface, high crystallinity, and thermal stability of TBG are verified by using comprehensive characterization techniques including optical microscopy, electron microscopy, and secondary-ion mass spectrometry. The proportion of TBG in bilayer graphene reaches as high as 89%. In addition, the stacking structure and growth mechanism of TBG are investigated, revealing that the second graphene layer develops beneath the first one. A series of comparative experiments illustrates that the liquid copper surface, with its excellent fluidity, promotes the growth of TBG. Electrical measurements show the twist-angle-dependent electronic properties of as-grown TBG, achieving a room-temperature carrier mobility of 26640 cm2 V-1 s-1. This work provides an approach for the in situ preparation of 2D twisted materials and facilitates the application of TBG in the fields of electronics. The local space-confined chemical vapor deposition growth technique for single-crystal TBG with a wide range of twist angles on liquid copper substrates is reported. The clean surface, high crystallinity, thermal stability, stacking structure, growth mechanism, and electrical transport properties of as-grown TBG are investigated. This work provides a convenient avenue for investigating the physical properties of TBG.image