Composition analysis of NdxFeyB thin films by RES and heavy ion ERDA

Thin sputter deposited layers with a nominal composition of Nd2Fe14B (thickness 120 to 400 nm) on Si/SiO2 were analysed by the combined application of RBS and heavy ion ERDA, These methods, based on elastic Coulomb scattering, are advantageous for composition analysis of thin compound layers due to their known cross sections, For high accuracy it is necessary that the spectral contributions of each element can be separated from each other and from the substrate background. This is difficult for light elements with RBS. The light element concentration however can be measured by ERDA with heavy incident ions, With 200 MeV I-127 ions from the Munich MP tandem the light elements as well as the Fe recoils were detected using a gas telescope. The Fe peak was used as cross reference to the RBS measurements. With 35 MeV Cl-35 ions at the 5 MV Rossendorf tandem too little energy is transferred to the Fe recoils to be identified with the Bragg ionisation chamber (BIC) detector. Therefore a thin aluminium layer was evaporated onto the Nd2Fe14B layer. The aluminium peak is well separated both in the RBS and in the ERDA spectra and is used as cross reference here.