Control of Si(100) Sublimation with Dopants

The sublimation of the Si(100)-( 2×1) surface under a tensile strain, induced by dopant segregation, was investigated with low-energy electron microscopy. At a given temperature, samples containing relatively large concentrations of dopants exhibit a step-flow behavior during sublimation. By contrast, the formation and proliferation of terrace vacancies, followed by a disintegration of the surface steps, dominates the sublimation of the lightly doped samples. Molecular dynamics simulations indicate that this striking difference in behavior is due to a strain-induced increase in the formation energy of dimer vacancies on the surface.