Density functional study of Ga intercalation at graphene/SiC heterointerface

The intercalation technique has harnessed tremendous attention in the 2D materials’ community, enabling to fabricate atomically thin and stable non-layered materials such as Ga at the heterointerface of graphene/SiC. However, the atomistic mechanism of the metal intercalation at such interface has still yet to been understood. In this study, first-principles calculations provide a thermodynamic and kinetic level understanding of the Ga penetration into and nucleation at the SiC/graphene interface. A Ga atom encapsulated at the graphene/SiC interface is thermodynamically more stable than adsorbed on the top of the graphene layer, signifying the necessity of exploiting the SiC substrate during the 2D Ga growth to facilitate the Ga migration into the SiC/graphene interface. Additionally, the sizes of a Ga atom and vacancy defect are critical to the Ga penetration through graphene, affecting the thermodynamic and kinetic preference of a Ga atom between the adsorption on graphene or the intercalation in to the SiC/graphene gallery. Graphical abstract: [Figure not available: see fulltext.].