Influence of CH4–Ar ratios on the composition, microstructure and optical properties of Be2C films synthesized by DC reactive magnetron sputtering

Beryllium carbide (Be2C) films were first deposited on optical quartz substrates by DC reactive magnetron sputtering on a beryllium target with variable CH4–Ar ratios. The influence of CH4–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 CH4–Ar ratios ( 15%). The films exhibited a nanocomposite structure consisting of Be2C 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 Be2C 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 Be2C films is presented, and the optical bandgaps were evaluated to be ∼2 eV. The good properties of Be2C films prepared by DC reactive magnetron sputtering showed that this material could be a potential candidate for application to inertial confinement fusion targets.