Hydrogen behavior in materials after single and triple-beam irradiations characterized by SIMS and µRaman

(1) CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette Cedex, France
(2) Groupe d’Étude de la Matière Condensée, CNRS and Université Versailles-Saint Quentin, 45 avenue des États-Unis, 78035 Versailles Cedex, France

Implantation of hydrogen in materials is used for several applications: in electronics for doping or thin film production and for nuclear studies to simulate gas accumulation during reactor operation. In the last case, interaction of hydrogen with the host matrix can cause damage through embrittlement, hardening, and swelling. During and after implantation, hydrogen diffuses and can be trapped, resulting in possible changes to its chemical bonding or molecular structure. In order to characterize the behavior of hydrogen implanted in depth in materials, we have combined two techniques. SIMS (Secondary ion mass spectrometry) is used for profiling H from the surface to about 5 µm in depth without any preparation of the sample. µRaman is applied on cross-sections of the samples. Mappings of Raman spectra as a function of the depth are obtained along the ion path evidencing possible matrix-H bonds or H2 molecular structure. This methodology has been applied to different materials: Si, SiC, Fe and ODS steel (Fe-12%Cr-4%Y2O3). We have observed in silicon the formation of Si-H and hydrogen-vacancy bonds. In SiC, we have observed in addition C-H bonds. In iron and the ODS steel, H profiles have been measured by SIMS but no Raman bands have been obtained in case of single beam irradiation. These results show that hydrogen is present in atomic form. Conversely, when ODS steel is irradiated in triple beam condition (Fe8+, He+, H+), H2 molecules are detected at a depth corresponding to the ion ranges, suggesting a synergistic effect between H and He or H and damages. Dual irradiations (Fe8+, H+) and (He+, H+) are in progress to discriminate these effects.