High-temperature desorption of C60covalently bound to6H-SiC(0001)-(3×3)

Abstract

The desorption or fragmentation temperature of C${}_{60}$ bound to Si-rich-($3\ifmmode\times\else\texttimes\fi{}3$) and ($\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})R{30}^{\ensuremath{\circ}}$ reconstructions of $6H$-SiC$(0001)$ is investigated using inverse photoemission spectroscopy (IPES) and LEED experiments. On SiC-($3\ifmmode\times\else\texttimes\fi{}3$), C${}_{60}$ film is found desorbed after annealing at a high temperature of 1140 K, supporting covalent bonding. Meanwhile, the Si tetramers of the ($3\ifmmode\times\else\texttimes\fi{}3$) nanostructured substrate are recovered, as can be inferred from the full reappearance of the Mott-Hubbard surface state in the IPE spectra. SiC-($3\ifmmode\times\else\texttimes\fi{}3$) behaves in a singular way among the other semiconducting substrates, which covalently bind to C${}_{60}$. This remarkable feature is attributed to the low density of Si dangling bonds and to the highly corrugated character of this reconstruction.