Surface modification without desorption: Recycling of Cl on Si(100)-(2 × 1)

Chlorine-induced modification of Si(100)-(2×1) was demonstrated under conditions where Cl was recycled rather than desorbed on SiCl₂. A dimer with 2SiCl, 2Cl atoms, converted to Si + SiCl₂, allowing the bare Si atom to escape. The SiCl₂ unit decayed through Cl diffusion at temperature below the desorption threshold allowing the second Si atom to escape. The result was terrace region with structures, a dimer vacancy and Cl. Access to this low energy pathway was controlled by Cl concentration and temperature.