In Situ Fabrication of h-BN/Graphene Heterostructures for Robust Electrical Performance in Atmospheric Conditions

Abstract Hexagonal boron nitride (h-BN)/graphene heterostructures offer an effective route to preserve the intrinsic electronic properties of graphene; however, direct chemical vapor deposition (CVD) growth of h-BN on graphene often leads to graphene etching and performance degradation. Here, we reported an in situ CVD strategy for fabricating large-area h-BN/graphene heterostructures by establishing a graphene dynamic growth-etching equilibrium during the h-BN deposition process. By continuously supplying a trace amount of carbon source, the graphene layer was maintained in a quasi-equilibrium state, effectively suppressing hydrogen-induced etching while preventing further lateral growth. The validity of this approach was further confirmed through a comparative analysis of Raman spectra collected at different growth stages. Comprehensive structural characterizations confirmed the high crystalline quality and uniformity of the h-BN/graphene heterostructures. Field-effect transistors (FETs) based on such heterostructures exhibited high carrier mobilities exceeding 20,000 cm2·V−1·s−1, low carrier concentrations below 3 × 1011 cm−2, excellent batch-to-batch reproducibility, and pronounced electron−hole symmetry. Importantly, h-BN/graphene devices demonstrated enhanced environmental stability under prolonged ambient exposure. Although a moderate decrease in mobility was observed during the initial ∼12 days, the devices subsequently exhibited remarkably stable electrical performance as the graphene layer remained effectively protected from further doping by the blocking effect of h-BN. Compared with bare graphene devices, h-BN/graphene devices exhibited higher carrier mobility and lower carrier concentration in atmospheric conditions. Such a growth-etching equilibrium strategy provides a general and scalable route for preserving graphene integrity during heterostructure growth and enables robust graphene-based electronic devices for long-term operation under ambient conditions.