Residual stress and laser-induced damage of ion-beam sputtered Ta2O5/SiO2 mixture coatings

• Ta2O5–SiO2 mixtures were deposited with a two-zone target ion-beam sputtering.
• Different ratios of Ta2O5–SiO2 mixture thin films are all amorphous.
• Reduction of compressive stress with addition of Ta2O5 in mixture was found.
• Laser-induced delamination is well improved with additional amount of SiO2 in Ta2O5.

An ion-beam sputtering apparatus was utilized to synthesize Ta2O5–SiO2 mixtures with a two-zone metallic Ta/Si target. Tailored refractive index monolayers with different Ta2O5/SiO2 ratios were deposited. The microstructure and residual stresses of different refractive index monolayers were studied by X-ray diffraction, transmission electron microscopy and interferometer. Reduction of compressive stress with addition of Ta2O5 in mixture monolayers was found. Improvement of laser-induced damage in the nanosecond regime i.e. less delamination of surface was found with more content of SiO2, which was believed to be the result of the thermodynamic and mechanic properties of SiO2 material.