Sublimation of a heavily boron-doped Si(111) surface

We investigated sublimation of a heavily boron-doped Si(111) surface in comparison with that of a normal Si(111) surface in ultrahigh vacuum. Step spacing during step-flow sublimation is analyzed as a measure of the adatom diffusion length using >50-μm-wide (111) planes created at the bottom of craters. On the heavily doped 1×1 surface, the step spacing is smaller and the step-spacing transition (or “incomplete surface melting” transition) temperature is 60° higher than those on the normal 1×1 surface. These results are interpreted in terms of the effect of boron at $S_5$ substitutional sites. Below 1100 °C, the sublimation of heavily doped surface on the wide terrace turns into a two-dimensional vacancy-island nucleation mode from step-flow sublimation observed above 1100 °C.