Peculiar covalent bonding of C 60 / 6H-SiC(0001)-(3 × 3) probed by photoelectron spectroscopy

F.C. Bocquet , L. Giovanelli (1) , Y. Ksari (1) , T Ovramenko (2) , A. Mayne (2) , Gérald Dujardin (3, 4) , F Spillebout (5) , Philippe Sonnet (5) , F Bondino , Elena Magnano , Jean-Marc Themlin (1)

1 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
2 ISMO - Institut des Sciences Moléculaires d'Orsay
3 PPM - Laboratoire de Photophysique Moléculaire
4 ISMO - Institut des Sciences Moléculaires d'Orsay
5 IS2M - Institut de Science des Matériaux de Mulhouse

High resolution photoemission with synchrotron radiation was used to study the interface formation of a thin layer of C60 on 6H−SiC(0001)-(3 × 3), characterized by protruding Si-tetramers. The results show that C60 is chemisorbed by orbital hybridization between the highest-occupied molecular orbital (HOMO) and the pz orbital of Si adatom at the apex of the tetramers. The covalent nature of the bonding was inferred from core level as well as valence band spectra. The Si 2p spectra reveal that a large fraction (at least 45%) of the Si adatoms remain unbound despite the reactive character of the associated dangling bonds. This is consistent with a model in which each C60 is attached to the substrate through a single covalent C60-Si bond. A binding energy shift of the core levels associated with sub-surface Si or C atoms indicates a decrease of the SiC band bending caused by a charge transfer from the C60 molecules to the substrate via the formation of donor-like interface states.

Domaines: Autre [cond-mat.other]

F.C. Bocquet, L. Giovanelli, Y. Ksari, T Ovramenko, A. Mayne, et al.. Peculiar covalent bonding of C 60 / 6H-SiC(0001)-(3 × 3) probed by photoelectron spectroscopy. Journal of Physics: Condensed Matter, 2018, 30 (50), pp.505002. ⟨10.1088/1361-648X/aaed1a⟩. ⟨hal-02314067⟩