Elastic recoil detection analysis of hydrogen with 7Li ions using a polyimide foil as a thick hydrogen reference

Elastic recoil detection analysis (ERDA) with an absorber foil using a 4.2 MeV 7Li2+ beam was utilized for evaluation of hydrogen depth profiles. Since recoil cross-sections when using Li ions as projectiles are not well known, the energy dependent ratio between the experimental yield and the yield calculated using the Rutherford recoil cross-section was obtained from an ERDA spectrum of a thick polyimide (Kapton) sample. It was estimated that this ratio does not significantly depend on sample composition. Therefore it was used for correction of measured spectra analyzed by existing simulation and evaluation programs in which the Rutherford recoil cross-sections were applied. The correction procedure has been verified in round-robin measurements of well-characterized Si:H thin layers. Application of the method for determination of a hydrogen depth concentration profile in hydrogen-containing graphite samples is presented.