Optimizing the Graphene/α-Al₂O₃(0001) Interface through Minimization of Interfacial Stress for Improved Electronic...

The direct integration of graphene onto technologically relevant insulating substrates is crucial for next-generation electronic and optoelectronic devices. Here, we present a density functional theory (DFT) study of the structural, electronic, and adhesion properties of graphene on the α-Al₂O₃(0001) surface. A 12-layer Al-terminated slab with two middle layers fixed is shown to provide an optimal balance between computational efficiency and accuracy, reproducing key surface properties such as work functions and electronic structures. The adsorption of graphene reveals a transition from planar to corrugated geometries with an increasing supercell size. Buckling notably modifies the local electronic structure, inducing a small bandgap and charge redistribution within graphene without significant charge transfer to the substrate. Energetics, corrugation patterns, and simulated scanning tunnelling microscopy images indicate that the interaction is dominated by weak van der Waals forces and lattice-induced modulation. Additionally, a rotated (R30) graphene configuration minimizes interface strain and exhibits enhanced stability. These findings offer valuable insights into the interfacial physics of graphene on dielectric oxides, relevant for applications in electronics, optoelectronics, and sensing.