Variation of the Er/Si ratio along the formation direction. Er content as a function of the distance from the PSi surface, as obtained from the SEM-EDS map shown in Figure 6 and performed on a 29-μm-thick porous Si layer. A linear decrease of the Er content is observed. The red line is a linear fit of the data that indicate a decrease of about 3%/μm.
Mula et al. Nanoscale Research Letters 2012 7:376 doi:10.1186/1556-276X-7-376