Determination of optical constants by angle scanning reflectometry

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optical Engineering

Background:

• Accurate optical constants (n, k) are crucial for understanding light-matter interactions in thin films.
• Previous studies on iron (Fe) films report optical constants that may be affected by surface oxidation.
• Reliable optical characterization requires methods robust against surface contaminants.

Purpose of the Study:

• To accurately determine the optical constants (n and k) of an iron (Fe) film.
• To develop and validate a measurement technique that mitigates the influence of surface oxide layers.
• To compare experimentally derived optical constants with existing literature values.

Main Methods:

• Reflectance measurements were performed on an Fe film across a broad spectrum of incident angles.
• A novel approach involved measuring reflectance through the substrate to circumvent surface oxide layer interference.
• Curve-fitting analysis, including rigorous chi-squared (x(2)) analysis, was employed to extract optical constants and their uncertainties.

Main Results:

• The optical constants (n and k) for the Fe film were successfully extracted with determined experimental uncertainties.
• The method effectively eliminated artifacts caused by surface oxide layers.
• Experimentally determined optical constants were found to be substantially larger than those reported in previous literature.

Conclusions:

• The substrate-transmission reflectance measurement technique provides accurate optical constants for Fe films.
• Higher optical constants suggest a need for re-evaluation of existing optical models for iron.
• This work establishes a reliable method for optical characterization of metallic thin films.