Arsenic-induced step rearrangements on vicinal Si (111) substrates

The orientational stability of stepped (vicinal) Si (111) surfaces during As exposure has been investigated using low-energy electron diffraction and Auger electron spectroscopy. When clean, Si (111) surfaces misoriented in the [2̄11] and [11̄0] directions are faceted, while those misoriented in the [21̄1̄] direction are step tripled. If these surfaces are equilibrated in an arsenic pressure, they all form orientationally stable step-doubled structures. However, exposure of the clean surfaces to As at temperatures<∼750 °C results in metastable structures with mixed step heights and/or facets.