Experimental comparison of extreme-ultraviolet multilayers for solar physics.

Area of Science:

• Materials Science
• Optics
• Thin Film Technology

Background:

• Extreme-ultraviolet (EUV) reflective coatings are critical for advanced optical systems.
• Multilayer coatings offer tunable optical properties for specific wavelength ranges.
• Existing materials face limitations in performance and stability.

Purpose of the Study:

• To compare the reflectance and stability of various multilayer coatings for EUV applications.
• To identify novel materials with enhanced spectral selectivity and thermal stability.
• To optimize multilayer designs for instruments like the Solar-B EIS.

Main Methods:

• Deposition of multilayer films (Si/Mo, Si/Mo2C, Si/B4C, Si/C, Si/SiC) using magnetron sputtering.
• Characterization of film properties via X-ray and EUV reflectometry.
• Comparison of experimental data with theoretical optical models.

Main Results:

• The silicon/silicon carbide (Si/SiC) multilayer exhibited the highest spectral selectivity at longer wavelengths.
• Si/SiC multilayers demonstrated superior thermal stability compared to other tested materials.
• Discrepancies were observed between experimental reflectance data and predictions using current optical constants.

Conclusions:

• Si/SiC multilayers represent a promising advancement for EUV reflective coatings due to their enhanced performance and stability.
• Further development of accurate optical models is necessary to fully predict multilayer performance.
• Optimized multilayer designs are crucial for the success of instruments like the Solar-B EIS.