Computational Modeling and Experimental Validation of Variabilities in Chemical Vapor Deposition of Graphene on Metals

Achieving laterally uniform graphene coatings via low-pressure chemical vapor deposition (LPCVD) remains challenging due to substrate-scale variations in near-wall transport that govern precursor renewal and local growth. Here, transient 3D CFD is coupled with spatially resolved characterization to examine how substrate inclination reorganizes near-wall transport in a hot-wall quartz-tube LPCVD reactor and its influence on graphene thickness uniformity. Across four substrate tilt angles (9°, 21°, 33°, and 45°), uniform coatings emerge not from maximizing flow intensity, but from establishing a laterally distributed near-surface transport field without significant downstream shielding. Shallow inclination (9°) produces weak surface-parallel transport and thicker boundary layers. In contrast, steep inclination (45°) induces strong but highly localized acceleration followed by wake-driven transport heterogeneity. Intermediate inclinations (21°-33°) yield more balanced near-surface velocity and wall shear stress distributions, promoting spatially uniform precursor renewal across the substrate surface. Raman mapping and SEM-based morphology analysis corroborate these transport trends, confirming reduced spatial segregation and improved thickness coherence within the 21°-33° inclination window. These findings establish a transport-based framework for interpreting substrate orientation effects in LPCVD graphene growth and provide reactor-level guidance for achieving uniform coatings in comparable hot-wall LPCVD systems.