Optical reflectivity of a PSi sample before and after the Er insertion. Comparison of the reflectivity spectra of the same sample before (red solid line) and after (green dashed line) the electrochemical insertion of Er (8% in this case). The effect of Er is a clear blueshift in the interference fringes (labeled Δλ) and a decrease in the absolute reflectivity of the Si-related peaks (labeled ΔR).
Mula et al. Nanoscale Research Letters 2012 7:376 doi:10.1186/1556-276X-7-376