The appearance and disappearance of small Ge clusters and missing dimer vacancies was observed on (001) surfaces during scanning tunnelling microscopy under standard tunnelling conditions at room temperature. It was claimed that these processes were instigated by the scanning tunnelling microscope tip. The observed features depended upon the W tip which was used, even if they were prepared in the same way and were used under the same tunnelling conditions. This suggested that the shape of the tip played a critical role.

H.J.W.Zandvliet, W.Wulfhekel, B.L.M.Hendriksen, B.J.Hattink, B.Poelsema: Physical Review B, 1998, 57[3], 1356-8