Influence of CH 4 –Ar ratios on the composition, microstructure and optical properties of Be 2 C films synthesized by DC reactive magnetron sputtering

Beryllium carbide (Be 2 C) films were first deposited on optical quartz substrates by DC reactive magnetron sputtering on a beryllium target with variable CH 4 –Ar ratios. The influence of CH 4 –Ar ratios on the composition, microstructure and optical properties were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, high-resolution transmission electron microscope, atomic force microscopy, scanning electron microscope and UV-vis spectrum. The main component in the films prepared at lower CH 4 –Ar ratios (15%). The films exhibited a nanocomposite structure consisting of Be 2 C nanocrystals (3 to 5 nm in size) embedded in amorphous hydrocarbon matrices. A smooth surface and columnar structure on the cross-sectional view were revealed. Besides, the depositing rates reached ∼125 nm h −1 , which were significantly higher than that of RF reactive magnetron sputtering. High transparency (>50%) of the Be 2 C films in the visible region as well as an even higher transparency (>80%) in the near-infrared region were demonstrated. Finally, the dispersion of the optical constants of Be 2 C films is presented, and the optical bandgaps were evaluated to be ∼2 eV. The good properties of Be 2 C films prepared by DC reactive magnetron sputtering showed that this material could be a potential candidate for application to inertial confinement fusion targets.