Pulsed laser deposition of diamondlike hydrogenated amorphous carbon films

Diamondlike hydrogenated amorphous carbon films have been deposited for the first time by pulsed ruby laser deposition (PLD) from pyrolytic graphite in hydrogen partial pressure. A hint in the IR absorption spectrum at 2920 cm−1 provides an evidence for the incorporation of hydrogen in the film. Raman scattering (RS) measurements display a large downward shift in the position of the intense G line to 1500 cm−1, whereas the relatively weak D line is observed near 1350 cm−1 along with a strong enhancement in RS near 1210 and 800 cm−1. These features are attributed to an increased proportion of tetrahedral (sp3) character in the amorphous carbon network due to formation of hydrogen-related complexes. Additional support for this proposal is sought from the enhanced band gap of the PLD a-C:H films compared to those of unhydrogenated PLD a-C films.