Excimer-laser irradiation produces amorphous diamond on graphite
Hungarian researchers at the JATE University department of optics and quantum electronics and in the research grou¥on laser physics of the Hungarian Academy of Sciences (both Szeged, Hungary) have used excimer-laser irradiation to form a thin, hydrogen-free, diamond-like carbon (DLC) layer on highly oriented pyrolytic graphite (HOPG). While providing properties similar to diamond films--which are expected to prove useful in future thin-film coatings--DLC films can be fabricated at lower temperatures and be tuned by deposition parameters.
In the experiment, a 193-nm-output, argon fluoride excimer laser irradiated a circular area about 70 µm in diameter on the HOPG substrate in air with 14-ns pulses at a laser fluence of 2 J/cm2. Afterward, area-selective Raman spectroscopy and atomic force microscopy revealed the presence of amorphous carbon in the irradiated area. The samples were then thermally annealed in air, which restored the crystal structure to the irradiated area.