Diffraction from small antiphase domains: α- [formula omitted], β- [formula omitted], 6×6 phases of Au adsorbed Si(111)

Abstract

Correlation between domain-wall configurations and electron diffraction patterns of the Au-adsorbed Si(111) surface was studied by scanning tunneling microscopy (STM), reflection-high-energy electron diffraction (RHEED), and low-energy electron diffraction (LEED) as a function of Au coverage. Streaks and rings around superreflections in α- 3 × 3 (LEED) patterns reflect the zigzagging feature and average size of the small 3 × 3 domains. These fine structures become diffuser and then convert to the β- 3 × 3 pattern in a continuous way with the increase of Au coverage. This evolution in the diffraction pattern is explained in terms of domain size contraction to a minimum size equivalent to six times of the substrate unit mesh. These smallest domains with dense antiphase domain walls in the β- 3 × 3 phase transform to the 6×6 phase by annealing around 600 K, where the smallest domains arrange in a long-range order. This structure transformation may be expressed as `recrystallization' in the arrangement of small antiphase 3 × 3 domains.