ELECTRONIC-PROPERTIES OF TETRAHEDRAL AMORPHOUS-CARBON (TA-C) FILMS CONTAINING NANOTUBE REGIONS

The electronic and optical properties of nitrogen doped tetrahedral am orphous carbon (ta-C:N) are compared with those of a new form of carbo n ta-C film in which nanotube regions are included (ta-C:(NT)). It is found that nanotubes in ta-C inhibit the N doping effect in ta-C and l eads to a reduction in conductivity. The results point to the nanotube regions acting as electronically isolated graphitic regions in ta-C. The refractive index in ta-C:(NT) is found to have the opposite depend ency on wavelength to that of ta-C. It is proposed that the refractive index can be used as a signature for the presence of nanotubes and ot her large graphitic regions in ta-C. (C) 1998 Elsevier Science Ltd.