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10 April 1995 Properties of laser-ablated amorphous carbon films
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Excimer laser ablation of a polycrystalline graphite target was used to prepare amorphous carbon films. Optical properties of the films were investigated in dependence of the laser power density and the hydrogen supply during deposition. The hydrogen content of the films was 0.7 to 37.5 at % in dependence of the deposition conditions. An optical bandgap up to 1.6 eV was found for films with low hydrogen content. Applying an additional hydrogen plasma during deposition the optical bandgap increased up to 1.95 eV. The laser power density was varied between 1.5 and 3.4 X 107 W/cm2. Generally, the lower power densities near the ablation threshold lead to larger optical bandgaps. An additional excimer laser irradiation of the growing carbon films with a laser power density up to 106 W/cm2 leads to graphitization within the otherwise amorphous films. An increase of the laser power density to 2 X 106 W/cm2 induce the formation of microcrystallites. Those microcrystallites could be identified as cubic diamond by means of transmission electron microscopy (TEM) investigations.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bernd Keiper, Steffen Weissmantel, Guenter Reisse, and S. Schulze "Properties of laser-ablated amorphous carbon films", Proc. SPIE 2403, Laser-Induced Thin Film Processing, (10 April 1995); doi: 10.1117/12.206249;

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