Charging effect during ion beam analysis: Comparison between aluminium and glass substrates

To avoid the charging effect of insulators during an ion beam analysis experiment, analysts currently cover the sample by a metallic film. We have analyzed the samples covered by gold using RBS. The energy profiles from backscattered He ions in different charge states allows us to illustrate the transformation of the insulator sample into a conductor. In this study, we have experimentally determined the optimal thickness of gold necessary for consistent measurements. We have showed that the gold layer must be at least 30 nm thick to ensure a reliable spectrum acquisition for the analysis of soda-lime glass.