Atomic-scale surface migration of a Ga atom on a H-terminated Si(100)-(2 x 1) surface was studied by using low-temperature scanning tunnelling microscopy and first-principles calculations. The Ga atom migrated in a linear potential well, confined by adjacent dimer rows and local dihydride defects, and was seen as a continuous linear protrusion (Ga-bar structure) in a narrow range of temperatures near to 100K. It was pointed out that the height of the Ga-bar structure mapped out the local variations in potential energy at individual adsorption sites.

Direct Observation of One-Dimensional Ga-Atom Migration on a Si(100)-(2 x 1)-H Surface - a Local Probe of Adsorption Energy Variation T.Hitosugi, Y.Suwa, S.Matsuura, S.Heike, T.Onogi, S.Watanabe, T.Hasegawa, K.Kitazawa, T.Hashizume: Physical Review Letters, 1999, 83[20], 4116-9