Influence of Surface Halogenation on Silane Adsorption onto Si(001) Surface for Poly-Si Epitaxy: A Density Functional Theory Study with Neural Network Potential

In this study, we conducted Density Functional Theory (DFT) simulations to investigate the impact of surface halogenation on the dissociative adsorption of SiH4 on crystalline Si(001) surface. First, we examined the adsorption energetics of surface halogenation using chlorine (Cl-2) molecules. The dissociative adsorption of Cl-2 exhibited a high reactivity with the undercoordinated surfaces without barrier. Molecular Dynamics (MD) simulations using Neural Network Potentials (NNP) has been developed and adopted to study surface diffusion of adsorbed Cl atoms and the surface concentration of Cl on the Si(001) surface at higher temperature. Second, we conducted subsequent silane (SiH4) adsorption and the first hydrogen dissociation on the bare and Cl-passivated surfaces. Our potential energy surface search revealed that the surface halogenation on the silicon surface suppresses the primary adsorption reaction of SiH4. Overall, this study provides an atomistic description of the dissociative adsorption mechanisms and associated energies of Cl-2 and subsequent SiH4 reactions for modeling the epitaxial deposition process and may serve as foundational knowledge for developing next-generation Si epitaxy techniques.