GALLIUM-INDUCED PERTURBATIONS OF THE GE(111)-C(2X8) RECONSTRUCTION

With the scanning tunneling microscope we investigated defects produced by small amounts of Ga on Ge(111)-c(2 x 8). The studied surfaces were prepared either using Ga-doped crystals (concentration up to 1 x 10(19) cm-3) or depositing Ga (up to 0.05 monolayer) from an effusion cell. Each surface area was studied in the constant-current mode for two different bias values (dual-polarity imaging), thus providing electronic and structural information for each defect. Ga atoms were found to substitute for rest atoms preserving the c(2 x 8) reconstruction. Defects in which adatoms occupy H-3 sites as well as those which break the c(2 x 8) long-range order are discussed.