Growth Kinetics of Gallium Selenide on Graphene: Bridging Atomistic and Mesoscale Processes

Achieving uniform, wafer-scale thin layers and heterostructures remains a major challenge in the synthesis of two-dimensional (2D) semiconductors, which requires precise control of growth parameters and atomic-level insight into surface interactions. We combine density functional theory (DFT) and kinetic Monte Carlo (KMC) simulations to investigate the early stages of 2D gallium selenide (GaSe) growth on graphene and determine how GaSe domain morphology, growth rate, and nucleation density depend on the atomic fluxes and substrate temperature. The presence of Ga on the substrate is key to promoting GaSe nucleation, while a sufficiently high Se flux is required to enable 2D GaSe growth and suppress accumulation of Ga clusters. The DFT-informed KMC simulations also reveal a trade-off between the growth rate and morphology, showing that increasing the flux of Ga relative to Se promotes faster growth of GaSe and increases the surface roughness. In contrast, high substrate temperatures promote edge healing and favor the formation of compact triangular domains. These results identify a narrow window of experimental conditions for 2D GaSe growth on graphene.