Thermal cycles, interface, chemistry and optical performance of Mg/SiC multilayers

The interplay between optical performance and the thermally activated interface chemistry of periodic Mg/SiC multilayers designed for application at 30.4 nm are investigated by optical (hard X-ray, soft X-ray and ultraviolet ranges, i.e. from 0.154 to 30.4 nm) reflectivity and X-ray emission spectroscopy. The multilayers are prepared by magnetron sputtering and then annealed up to a temperature of 500 °C. Two clear changes take place in the multilayer upon annealing. At first, between 200 and 300 °C a strong decrease of the reflectivity is observed, due to the development of interfacial roughness following the crystallization of the Mg layers. No interfacial compound is detected. Then, between 350 and 400 °C there is formation of the Mg