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

Twisted bilayer graphene (TBG) has generated significant attention in the fundamental research of two-dimensional (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 moiré materials. Here, we reported the local space-confined chemical vapour deposition growth technique for high-quality single-crystal TBG with twist angles ranging from 0 to 30° on liquid copper substrates. The clean surface, pristine interface, high crystallinity, and thermal stability of TBG were verified by using comprehensive characterization techniques including optical microscopy, and electron microscopy, secondary-ion mass spectrometry. The proportion of TBG in bilayer graphene reached as high as 89%. In addition, we investigated the stacking structure and growth mechanism of TBG, revealing that the second graphene layer developed beneath the first one. A series of comparative experiments illustrated that the liquid copper surface, with its excellent fluidity, promotes the growth of TBG. Electrical measurements showed the twist-angle-dependent electronic properties of as-grown TBG, achieving a room-temperature carrier mobility of 26640 cm 2 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. This article is protected by copyright. All rights reserved.