Investigation of thin films by soft X‐ray fluorescence and by total electron yield measurements

Abstract

AbstractWe propose a description of the sampling depth (λ) of total electron yield experiments (TEY) in terms of kinetic Auger electron energies. This empirical response results from literature data1 – 6 on low energy (<2 keV) and from our own experiments performed on thin layers of Cu on Fe substrates and on thin layers of AlxGa1 − xAs on GaAs substrates at energies of approximately 5to 8 keV. From these investigations we estimate a sampling depth of 74 nm for Ga KLL Auger electrons in AlxGa1 − xAs. For comparison, the sampling depth of x‐ray fluorescence analysis (XRF) for Al Kα radiation in AlxGa1 − xAs is 400 nm.Both methods (XRF and TEY) were joined for quantitative determination of the thickness t and the Al content x in thin AlxGa1 − xAs layers on GaAs substrates. Al Kα fluorescence radiation excited by polychromatic x‐radiation and the jump of the total electron yield in the vicinity of the GaK‐edge were used in our analytical model. The validity of this model is verified by a comparison of our results with the expected values (known from preparation of the layers).