  The vicinal Si(111) surface, inclined towards the [-1-12] direction, was
investigated by scanning tunnelling microscopy and spot profile analysing low
energy electron diffraction. It has been established that the surface,
consisting of regularly spaced triple steps and (111) terraces with a width
equal to that of a single unit cell of the Si(111)-7x7 surface structure, has
the (7 7 10) orientation. An atomic model of the triple step is proposed.
