C60-induced reconstruction of the Ge(111) surface

Orientation ofC60molecules in the(33×33)R30Fanetti1, Gavioli2, Cepek3 et al. 2008Phys. Rev. B5040View full textAdd to dashboardCite

“…Xu et al explained this discrepancy by supposing that a reconstruction of Ge͑111͒ adatoms is responsible for the R3 LEED pattern. 1 In contrast, Goldoni et al suggested that the observed R3 periodicity is due to an alternating orientation of the molecules. 2 In this model, which will be discussed in the next section, the different molecular orientations are determined by different substrate atom configurations in each adsorption site.…”

“…In this case, the molecular lattice observed by STM is a hexagonal lattice with a lower density with respect to the former ͑molecular lattice unit vector: 1.44 nm͒ and the observed R13 LEED pattern is consistent with the lattice periodicity observed by STM. 1 For this reason, no long-range extra periodicity due to the molecular orientation is expected in this case.…”

“…The former is obtained by annealing ͑or depositing͒ a multilayer C 60 film at 450-500°C. 1 The latter is obtained by annealing ͑or depositing͒ a C 60 multilayer at more than 500°C, 1 up to the single layer desorption temperature, which on Ge͑111͒ is ϳ670°C. 8 After the annealing in this temperature range, only a single molecular layer is still present on the substrate because the layers above are desorbed from the surface at a temperature close to the sublimation temperature of bulk C 60 in vacuum, which is ϳ230°C.…”

“…2,[13][14][15][16] As a consequence, several studies are present in the literature devoted to investigating how the C 60 molecules are oriented with respect to the substrate and how the orientational degrees of freedom play a role in the resulting periodicity and/or symmetry of the system. 9,[13][14][15][17][18][19][20] The C 60 adsorption on Ge͑111͒-c͑2 ϫ 8͒ surface has been studied by x-ray diffraction, 7 low energy electron diffraction ͑LEED͒, 1,8 scanning tunneling microscopy ͑STM͒, 1,4,5 and spectroscopy techniques such as x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy ͑UPS͒. 2,8 Two different ordered molecular configurations have been observed, 1 depending on the preparation temperature: the ͑3 ͱ 3 ϫ 3 ͱ 3͒R30°phase and the ͑ ͱ 13ϫ ͱ 13͒R14°phase, defined with respect to the Ge͑111͒-͑1 ϫ 1͒ unit cell.…”

Investigation of mode localization in hybrid periodic/quasiperiodic heterostructures containing nano-scale fullerene layers

“…This property of C60 fullerenes can be utilized for the fabrication photonic crystal structures using the fullerenes films. High-quality C60 thin films have been grown on various semiconductor and metal substrates, such as Te [21], Ge [22], GaAs [23], Ag [24] and so on. C60 thin films have almost zero absorption in the wavelength range> 530 nm and near IR region [25].…”