A hybrid neural network model is constructed by characterizing the growth of GaAs 1 P -GaAs superlattices (SLs) grown on (001) GaAs substrates by molecular beam epitaxy. These heterostructures are formed by the P 2 exposure of an As-stabilized GaAs surface, and ex situ high-resolution X-ray diffraction (HRXRD) is performed to determine the phosphorus composition at the interfaces. A first-order kinetic model is then developed to describe the mechanisms of anion exchange, surface desorption, and diffusion. A semi-empirical hybrid neural network is used to estimate the parameters of the kinetic model and analyze the microscopic processes occurring at the interfaces of the mixed anion III-V heterostructures. The phosphorus diffusion process in GaAs is estimated to have a diffusion coefficient of = 1 4 10 14 exp( 0 11 eV ) cm 2 s 1 for samples with As = 4 10 6 torr and exhibits enhanced phosphorus intermixing for samples with lower As-stabilizing fluxes.Index Terms-Anion exchange, hybrid neural networks, kinetic modeling, molecular beam epitaxy.