Characterisation of compact discs using time of flight-energy elastic recoil detection analysis

The challenge of meeting the ever increasing demands for low-cost information storage media with greater information storage density and rapid access has prompted development of sophisticated optical technologies, e.g., compact disc (CD) and digital video disc (DVD) in read only memory (ROM), recordable (R), rewritable (RW) and random access memory (RAM). Here the suitability of time of flight-energy elastic recoil detection analysis (ToF-E ERDA) to characterise optical storage media film has been investigated. High-energy heavy ions (48 MeV Br-81(8+) and 60 MeV I-127(10+)) from a tandem accelerator were used to analyse CD-ROM, CD-R and CD-RW structures. Up to 9 elements, H, C, O Al, P, Co, Cr, Ge, and Sb/Te could be distinguished simultaneously. The results demonstrate the unique power of the technique for characterising the composition and depth profile of the optical multi-layers as well as the ingress and influence of foreign species.