DFT-Assisted Approach to Low-Temperature Graphene Growth on Sapphire

Controlling the direct growth of 2D materials onto dielectric substrates is considered as a key requirement for integrating these ultrathin functional materials into existing technology platforms. Here, a combined experimental and theoretical approach is presented to unravel the mechanism of low-temperature graphene growth on sapphire, a dielectric substrate widely used in the semiconductor industry. A clear dependence of the graphene growth rate on the crystal facet is found, with the highest growth rate for a-plane and ca-plane, and the lowest for r-plane sapphire. Density functional theory calculations reveal that the coordination environment of surface oxygen ions governs carbon adsorption energetics: lower coordinated oxygen sites on the a-plane markedly enhance carbon atom binding, driving nucleation and growth, while higher coordinated oxygen sites on the r-plane hinder adsorption and growth. Guided by these insights, it is demonstrated that tailoring substrate termination yields controllable graphene formation at temperatures as low as 670 °C and sheet resistances down to 1.65 kΩ □^-1. This approach may establish a universal design principle to guide low-temperature growth of 2D materials on non-catalytic dielectrics.