Insight in the outside: materials science at the atomic level using LEIS

Modern low energy ion scattering (LEIS) can provide new information on the atomic composition of both outermost surface and sub-surface layers. The wide scope of new possibilities is illustrated with results on ceramics, polymers and ultra-thin layers. Most of the results presented are difficult or even impossible to obtain otherwise. The combination of LEIS and isotopic oxygen exchange reactions was used to investigate the surface of yttria stabilised zirconia (YSZ) that is used in the solid oxide fuel cell. It is found that under working conditions the surface is covered by a monolayer of contamination, followed by an yttria segregated layer. The quantification of LEIS is demonstrated for fluorinated self-assembled monolayers, while also the conformation of the endgroups is determined. The use of LEIS to follow the growth of ultra-thin layers is discussed for a TiN barrier layer on silicon.