Surface Modification without Desorption: Recycling of Cl on [Formula presented]

We demonstrate chlorine-induced modification of [Formula presented] under conditions where Cl is recycled rather than desorbed as [Formula presented]. A dimer with 2 Cl atoms, 2SiCl, converts to [Formula presented], allowing the bare Si atom to escape onto the terrace. At temperatures below the desorption threshold, the [Formula presented] unit decays through Cl diffusion, allowing the second Si atom to escape. The result is a dimer vacancy, terrace regrowth structures, and Cl that is able to participate in another pitting event. Access to this unexpected roughening pathway is controlled by the Cl concentration and temperature. This previously overlooked process represents an important component of Si(100) surface processing.