Sampling depth of total electron and fluorescence measurements in Si L- and K-edge absorption spectroscopy

High resolution Si L-edge and K-edge X-ray absorption near edge structure (XANES) spectra for SiO2 on Si substrates have been recorded using total electron yield (TEY) and fluorescence yield (FY) techniques. The sampling depths of TEY and FY for Si L-edge and Si K-edge, respectively, have been investigated in the energy range 95-120 eV and 1830-1900 eV. The maximum sampling depth for TEY is found to be similar to 5 nm for the Si L-edge and similar to 70 nm for the K-edge regions. The FY sampling depth at the L-edge is similar to 70 nm whereas for the K-edge, the sampling depth is several hundred nm. Based on these data, and using a theoretical model, electron escape depths for the TEY measurements in both energy ranges have been deduced.