Hydrogen-Containing Amorphous Carbon Layers as Optical Materials in the Near-IR Spectral Range

Hydrogenated amorphous carbon layers were deposited on various substrates by means of a plasma CVD process with a RF substrate bias as well as an ECR plasma source. The optical properties of the a-C: H layers were obtained via spectroscopic ellipsometry and correlated with their mechanical and chemical properties. The layers from pure RF plasma exhibit a higher absorption constant in the visible spectral range and a higher refractive index. All layers are nearly transparent in the NIR spectral range making them candidates for optical thin layer systems. The laser damage behaviour of the a-C: H layers was investigated with ultrashort pulses. The damage thresholds were consistent with the absorption constants of the layers. Interesting damage morphologies were observed indicating a sensitivity of this experiment to sub-structures in the layer.