RBS Analysis of Down-conversion Layers Comprising Two Rare-Earth Elements

Publication date: 2017 Source:Physics Procedia, Volume 90 Author(s): David C. Ingram, Wojciech M. Jadwisienczak, Florian Ehré, Christophe Labbé, Fabrice Gourbilleau Rutherford Backscattering Spectroscopy (RBS) of samples containing two rare-earth elements is difficult owing to the small mass separation of even the lightest and heaviest members of the group. In studies of the growth of silicon nitride down-conversion layers, compatible with silicon photovoltaic technology, 2-3 MeV RBS has been combined with RBS at 5 MeV and alpha PIXE, to determine the composition of samples grown with different amounts of cerium and ytterbium. The films were produced using reactive magnetron co-sputtering. Conventional RBS at 2.2 MeV is used to determine the nitrogen and oxygen and silicon content of the films. At this energy, elements from carbon upwards have scattering cross-sections determined by the Coulomb potential. However, the cerium and ytterbium peaks at this energy merge into one and make it very difficult to determine the ratio of these elements and the absolute amount of each element. At 5 MeV sufficient separation was achieved between the cerium and ytterbium peaks that their ratio and absolute amount could be measured. At this energy the scattering from these elements is still determined by the Coulomb potential. For all the other elements in the sample the Coulomb barrier has been exceeded such that data from them is unusable. Care also needs to be taken to ensure the...

Source: Physics Procedia - October 26, 2017 Category: Physics Source Type: research