Moire engineering for grain boundary design in graphene

Deterministic control of graphene atomic structure would enable the precise tuning of its electrical, mechanical, and thermal properties. Current synthesis methods like chemical vapor deposition, however, have limited atomic control due to a lack of mechanistic insight on defect formation due to synthesis conditions. Furthermore, it is impossible to observe atomic scale mechanisms during synthesis due to the incompatible time scales of growth and microscopy. In our work, we overcome these challenges by coupling atomic scale mechanistic models with moiré engineering to enable experimental observation of atomic scale defects during synthesis. We present an application of this technique to tailoring graphene grain boundaries during synthesis. Our method introduces a mechanistic atomic scale model for the formation of graphene grain boundaries during graphene nuclei coalescence. The atomic scale models are promoted to the nanoscale to create the moiré engineering technique that addresses the incompatible time scales and enables real-time observation of atomic scale defects. We showcase this technique using in-operando scanning tunneling microscopy data of graphene grown on rhodium and show how it can enable real-time decision making under scalable synthesis conditions of graphene.