AMORPHOUS-CARBON FILM DEPOSITION BY LASER-INDUCED C-60 FRAGMENTATION

It is demonstrated that a pure carbon (fullerene) precursor, C-60, is appropriate for laser-induced carbon film deposition. Amorphous carbon films were obtained on Si and SiO2 substrates upon ArF excimer laser induced fragmentation of gas phase C-60. The depositions were performe d in Ar and H-2 ambient in a hot-wall reactor at 550 degrees C. Strong C-2 emission bands were observed by optical emission spectroscopy dur ing the deposition process indicating that C-2 dimers are used for fil m formation, however, thermal decomposition of C-58, C-56, etc. high-m ass fragments may also contribute to the layer development. Raman and TEM studies showed amorphous (highly disordered, turbostratic) charact er of the films. Optical absorption spectroscopy indicated semiconduct or feature of the layers with optical band gap of 0.7 and 0.9 eV for t he films deposited in Ar and H-2 ambient, respectively. For the films deposited in H-2 atmosphere, changes in the Raman spectrum and an upsh ift of the optical band gap of the layer indicate amorphous hydrogenat ed film with diamond-like character, however, degree of the sp(3) hybr idisation was estimated to be low. The deposition rate was measured to be similar to 200 Angstrom/min at 500 degrees C and 400 mJ/cm(2) lase r fluence. AFM measurements showed smooth films with low surface rough ness, similar to 1 nm on 1 mu m scale length.