NITROGEN DOPING OF TETRAHEDRAL AMORPHOUS-CARBON

N has been found to be an effective n-type dopant of tetrahedral amorp hous carbon, ta-C. Molecular orbital diagrams and band calculations ar e used to describe the electronic structure of various C-N bonding con figurations and account for the doping mechanism. The doping configura tion of N at low concentrations is the substitutional, sp(3) coordinat ion. The doping efficiency is estimated to be about 1%. Two possible n on-doping configurations of N, the trivalent and the compensated are b oth consistent with the electron energy loss spectra. Both N and C ado pt graphitic bonding a high N concentrations.