A Comprehensive Atomistic Picture of the As-Deposited Ni-Si Interface Before Thermal Silicidation Process

•Atomistic picture of the as-deposited alloyed interface layer during nickel silicidation process.•Combination of experimental and numerical approaches to unravel the early stages of nickel silicide formation.•An interface alloyed layer with a nickel-rich Ni3Si composition is formed even at room temperature before any thermal activation.•Ability of nickel atoms to penetrate the surface layers of the silicon substrate.