Investigation of oxide layer structure on niobium surface using a secondary ion mass spectrometry

Oxide layer structure on the surfaces of niobium (Nb) can be studied by continuously monitoring peaks of the secondary ions of Nb and its relevant oxides as a function of time during depth profiling measurements employing a secondary ion mass spectrometry (SIMS). This is based on the fact that different oxides have different cracking patterns. This new approach is much simpler and easier for studying oxide layer structure on Nb surfaces than the conventional approach through deconvolution of oxide peaks obtained from an X-ray photoelectron spectroscopy. Eventually the method described here can be developed into an in situ tool for monitoring the oxide layer structure on Nb surfaces prepared by various procedures. Preliminary results of SIMS measurements on the surfaces of Nb samples treated by buffered electropolishing and buffered chemical polishing will be reported.