Initial oxidation stage of the Ge 100/2=1 surface studied by scanning tunneling microscopy and ultra-violet photoelectron spectroscopy

The initial stage of oxygen chemisorption on the Ge 100.surface and its annealing behavior were studied by scanning tunneling microscopy STM.and ultra-violet photoelectron spectroscopy UPS.. Atomically resolved dark and bright sites were identified by the interaction at room-temperature exposure to molecular oxygen. These surfaces showed a prominent peak at 4.6 eV in the UPS spectra. After annealing at 3008C, the oxygen-induced products clustered along the dimer rows and formed an aligned dark structure. Isolated bright products still remained, and some of them were the same as those on the room-temperature exposure. UPS spectra showed a shift on the peak energy to 5.5 eV, indicating that a stable Ge–O–Ge complex has been formed by the annealing. q1998 Elsevier Science B.V. All rights reserved.