EFFECTS OF NITROGEN DOPING ON THE GROWTH AND PROPERTIES OF PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITED DIAMOND-LIKE-CARBON FILMS

Nitrogen-doped diamond-like carbon (DLC) or amorphous hydrogenated car bon (a-C:H) films were grown by plasma enhanced chemical vapor deposit ion using methane and nitrogen gases as precursors. The effects of nit rogen trifluoride (NF3) on these nitrogen-doped DLC films were also in vestigated. The deposition rate decreases sharply with the addition of nitrogen in the absence of NF3 due to dilution, while it increases in the presence of NF3 due, presumably, to the reduction of activated hy drogen species by the fluorine radical (F-). X-ray photoelectron spect ra reveal a nitrogen concentration in the range of 9.3 to 13.8% in the se DLC films with a C Is electron binding energy of 287-288 eV, indica ting the diamond-like structure. Infrared spectra of DLC films indicat e the presence of amino groups (N-H) and nitrile and/or isonitrile (C= N) groups giving strong evidence of sp carbon. Diamond like carbon fil ms deposited in CH4+N2, (with and without NF3) have a lower refractive index, a lower bulk resistivity, and a lower optical bandgap than fil ms deposited using CH4 due to a lower hydrogen content in the films. M oreover, the bulk resistivity of these films decreases by over four or ders of magnitude and the optical bandgap decreases from 2.65 eV to ab out 0.75 eV following annealing at a temperature of 500-degrees-C.