Hetero-site nucleation for growing twisted bilayer graphene with a wide range of twist angles

Abstract

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.

Recent Progress on Two-Dimensional Materials

“…To achieve this, the fabrication of MATBG devices should avoid high temperature, the formation of bubble between two graphene layers, and the additional strains. Note that, CVD approach, which is suitable for the production of graphene films on a large scale, is also capable of growing twist bilayer graphene 645 . However, it remains difficult to produce twist bilayer graphene with fine control over twist angle, especially the magic angle near zero, owing to the overwhelming stability of AB-stack bilayer graphene.…”

Precise CO2 Reduction for Bilayer Graphene

“…We can also observe sharp edges of the BLG domains through optical microscopic images. 32 The AB-stacked BLG domains account for ∼75%, and the rest are mostly 30° twisted angles ( Figures S5 and S6 ). It had been reported that the orientation of the second graphene layer can be affected by the environment of graphene growth, such as the variation in gas flow and distinct interface energy between the adlayer graphene and graphene/Cu steps.…”

Challenges and opportunities in 2D heterostructures for electronic and optoelectronic devices

“…However, the progress in this direction is not promising as most of the structures obtained either have the R-type (0°) stacking orientations or the H-type (60°) stacking orientations, as they are energetically favorable in the CVD growth process ( Liu et al., 2014 ). Few strategies, including heterosite nucleation ( Sun et al., 2021 ), temperature triggered misalignment ( Omambac et al., 2019 ), metal-semiconductor stacking ( Li et al., 2020a ), epitaxial intercalation of graphene under hydrogen-terminated hBN template ( Wang et al., 2021a ), are recently reported that showed the potential of CVD to generate moiré phase. Still, stringent control on interlayer twist angle is challenging and needs to be encountered soon.…”