Scanning tunnelling microscopy was used to study domain boundaries on (111) 7 x 7 surfaces. Several types of regular defect structure along the domain boundaries on such surfaces were observed at atomic resolution. By combining the results with the dimer-adatom stacking fault model, detailed atomic structural models were derived. It was found that there were 3 important factors which determined the boundary structure. The most important one was the strong interaction between dimer and adatom. The second most important one, in some cases, was the difference between the faulted half and the unfaulted half. Finally, metastable (2n+1) x (2n+1) triangle sub-unit structures such as 5 x 5 could sometimes play an important role in determining the defect structure along the domain boundary.

Q.J.Gu, W.B.Zhao, Z.L.Ma, N.Liu, Z.Q.Xue, S.J.Pang: Journal of Vacuum Science and Technology B, 1995, 13[3], 1261-4