A study was made of Ge coverage (θGe) dependent quenching, reactivation of flip-flop motion and interaction with dimer vacancy lines of dimers on Ge/Si(001) surfaces, by using scanning tunneling microscopy combined with molecular beam epitaxy. The deposition of about 0.3ML of Ge quenched flip-flop motion and made all of the dimers asymmetrical. Further deposition introduced dimer vacancy lines when θGe was greater than about 0.5ML, and symmetrical dimer domains again appeared locally when θ was greater than 1.5ML. High-resolution scanning tunnelling microscopic images indicated that asymmetrical dimer rows always inverted their phase in alternation with the buckled dimer up-end at the dimer vacancy lines. Low-temperature scanning tunnelling microscopic images indicated that the symmetrical dimer domains were due to the flip-flopping of asymmetrical dimmers, activated by a large θGe at room temperature. The symmetrical dimer domains extended along the dimer rows over the dimer vacancy lines, due to the phase correlation.

Dimers at Ge/Si(001) Surfaces - Ge Coverage Dependent Quenching, Reactivation of Flip-Flop Motion and Interaction with Dimer Vacancy Lines. H.Hirayama, H.Mizuno, R.Yoshida: Physical Review B, 2002, 66[16], 165428 (5pp)