In Situ Growth Dynamics of Uniform Bilayer Graphene with Different Twisted Angles Following Layer-by-Layer Mode

Synthesis of large-area uniform bilayer graphene (BLG) with different twisted angles has gathered extensive interest but remains a challenge, hindered by the ubiquitous layer-plus-island growth and the uncontrollable layer rotation. Herein, using real-time surface imaging, film uniformity and stacking structures in BLG were well controlled by a two-step carbon segregation on Ni(111) films following the layer-by-layer growth mode. The aligned first graphene layers formed at 850 degrees C through a thermodynamics-limit process, followed by decreasing temperatures to grow the second layers, eventually enabling the extremely uniform 15 degrees-twisted BLG at 790 degrees C and AB-stacked BLG at 720 degrees C, respectively. Essentially, the growth dynamics is perceived to determine that for the different stacking structures, nonaligned second layers are more kinetically preferable than aligned ones at relatively high temperatures, but the case reverses at low temperatures. This work conveys a fundamental dynamic understanding of the controllable integration of uniform BLG and tuning stacking structures.

Automated summary

In this study, the layer stacking structures and film uniformity of large-area uniform bilayer graphene (BLG) were successfully controlled through a two-step carbon segregation method. Using real-time surface imaging and thermodynamics-limit process, the growth of extremely uniform 15 degrees-twisted BLG and AB-stacked BLG were achieved at specific temperatures.