Controlling the local electronic properties of Si(553)-Au through hydrogen doping

We propose a quantitative and reversible method for tuning the charge localization of Au-stabilized stepped Si surfaces by site-specific hydrogenation. This is demonstrated for Si(553)-Au as a model system by combining density functional theory simulations and reflectance anisotropy spectroscopy experiments. We find that controlled H passivation is a two-step process: step edge adsorption drives excess charge into the conducting metal chain `reservoir' and renders it insulating, while surplus H recovers metallic behavior. Our approach illustrates a route towards microscopic manipulation of the local charge distribution within the surface structure and establishes a reversible switch of site specific chemical reactivity and magnetic properties on vicinal surfaces.