Spontaneous roughening of low-coverage Si(100)-2x1:Cl surfaces:: Patch formation on submonolayer halogenated surface -: art. no. 205432

It is well established that fully halogenated Si(100) surfaces undergo spontaneous roughening upon annealing due to steric repulsions between halogen filled dimers. However, roughening has also been reported at low halogen coverages where steric effects are unexpected. Here we demonstrate that surface roughing shows a hyperlinear correlation with coverage, indicating that repulsions are important even at coverages significantly below a monolayer. This behavior is attributed to a clustering phenomenon that drives halogen atoms to form surface patches despite the presence of steric interactions. A correlation between the emergence of surface patches and the onset of roughening is presented. However, a detailed model of submonlayer surface roughening is still lacking.