Trapping of implanted He at Cu/Nb interfaces measured by neutron reflectometry

Neutron reflectometry is used to characterize physical vapor deposited [Cu/Nb](x)/Si layered nanocomposites exposed to extreme helium ion doses. The effects of He ions on the interfacial roughness, layer swelling, and chemical mixing have been measured. Regions of high He concentration were localized at Cu/Nb interfaces while bulk Cu and Nb layers remained intact. This remarkable behavior is attributed to the efficient trapping and storage of He at interfaces as compared to bulk. (C) 2011 American Institute of Physics. [doi:10.1063/1.3600642]