Peculiar properties of preferential sputtering of PbTe, SnTe, and GeTe by Ar+ ion plasma

Sputtering of PbTe, SnTe and GeTe compounds having both small and large differences in the individual components' masses by Ar+ plasma under Secondary Neutral Mass Spectrometry (SNMS) conditions are investigated. The effect of preferential sputtering and its peculiar features caused by the different ratios between masses of the IVB atoms and tellurium were observed. The method and the empirical relationships for determination of the relative detection factor (RDF) of the intrinsic components of the compounds are suggested. It is shown that RDF of Te and metal species of the investigated samples isn't a constant, but depends on sputtering energy. These dependences are explained by the changes of the sputtering surface morphology and the impact of mass of the sputtered species on the fraction of the species flux ejected into the solid angle collected by the spectrometer mass analyzer. The limits of applicability of SNMS for quantitative analysis of composite samples with big differences in masses of their constituents are established. A possible solution for such cases is proposed. It is shown that in the sequence of PbTe-SnTe-GeTe compounds the surface binding energy of the metal components decreases in the direction from lighter to heavier atom.