Self-organization of steps and domain boundaries of 7x7 reconstruction on Si(111)

We describe three different aspects of the self-organization of steps and domain boundaries of a 7x7 reconstruction on Si(111) surfaces. The first is the formation of a triangular-tiled pattern of '1x1' and 7x7 domains during the phase transition. '1x1' and 7x7 domains have different surface stresses. The triangular-tiled pattern is stabilized through stress relaxation. The second is the step arrangement inside a hole, which was fabricated by a standard lithographic technique. The step arrangement in the hole depends on the temperature. Below the '1x1'-to-7x7 phase transition, the hole has a three-fold symmetry consisting of step-bunched and non-bunched regions. This is because the step arrangement on the vicinal Si(111) surfaces depends on the direction of the steps. The third aspect is the formation of a pattern of steps and domain boundaries induced by Si growth. During the step-flow growth on Si(111), steps preferentially protrude along the domain boundaries on the lower terrace. The resulting changes in step shape induce a unique rearrangement of the domain boundaries, the number of which decreases during growth. However, when a periodic pattern is formed in the initial stages, it remains stable during growth.