Ultra-high Resolution Elemental Mapping of Si-core-C-shell Silicon Nanoparticles

Very low beam current and/or very short measurement time are needed for SEM-based EDS analysis of beam sensitive samples, such as Si nanoparticles. It is necessary to use low voltage to reduce the electron-sample interaction volume when high spatial resolution is required. For conventional EDS measurement, such analytical conditions are challenging since the induced X-ray yield is very low and thus demand very long measurement time. The consequence is beam-induced sample drift which affects the spatial resolution. 

EDS measurement performed with XFlash^® FlatQUAD overcome these limitations. The unique geometry of the XFlash^® FlatQUAD enables high detection sensitivity for low x-ray yield materials, giving high count rates at low probe currents. Thus, the XFlash^® FlatQUAD detector is ideal for mapping beam-sensitive materials even with topography. 

This example presents a high-resolution map (pixel spacing of 2 nm!) of silicon nanoparticles. Mapping was done with a XFlash^® FlatQUAD at 5 kV, 520 pA and 377 s acquisition time. The results indicate that the present nanoparticles are characterized by a silicon core (green) and a carbon shell (red). (Data courtesy:  S.Rades et al., Royal Society of Chemistry Advances, 2014, 4, 49577)