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

Abstract

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 moiré materials. Here, the local space‐confined chemical vapor deposition growth technique for high‐quality single‐crystal TBG with twist angles ranging from 0° to 30° 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.

Atomic engineering of two-dimensional materials via liquid metals

“…Liu et al reported another novel method for producing high-quality single-crystal tBLGs with twist angles ranging from 0° to 30° using a local space-confined CVD growth technique on liquid Cu substrates. 265 The schematic diagram of the local space-confined strategy is shown in Fig. 18d.…”

Growth and applications of graphene on copper

“…Recently, because of the unique properties of liquid Cu, self-aligned graphene nanoribbons with widths down to sub-10 nm and aspect ratios up to 387 were fabricated via a template-free CVD route. 12 In addition, the growth of single-crystal twisted bilayer graphene on liquid Cu was achieved, 13 exhibiting superior thermal stability and carrier mobility as high as 26,640 cm 2 V −1 s −1 . Overall, the dynamic and rheological nature of the liquid Cu enables the graphene islands to rotate, move, and align freely, which provides an important platform for the orientation control in the growth of single-crystal graphene.…”