On the structural and electronic properties of fluorinated carbon allotropes

The structure and electronic properties of different fluorinated forms of c arbon are investigated using density-functional based tight-binding (DFTB) calculations. For graphite, the F interstitial disturbs conduction paths in the carbon plane. This explains the experimentally observed drop in conduc tivity during intercalation of graphite with F. In the case of tetrahedrall y bonded amorphous carbon (ta-C), fluorination does not lead to improvement of the doping capabilities, in contrast to the amorphous hydrogenated sili con system. Moreover, F addition causes a degradation of the structure and there is no correlation between stress indicators on a microscopic scale an d F content up to 11 at.%. Regarding the single-wall carbon nanotubes (SWNT s), sidewall functionalization yields tubes with a wide variety of electron ic properties, ranging from insulators over semiconductors to metallic form s. A chemical derivative of such tubes opens perspectives for tailoring the ir electronic properties.