RBS study on Na-implanted polystyrene at various doses

A study on the composition of Na-implanted polystyrene has been made by Rutherford backscattering spectroscopy (RBS). Substrates used were polystyrene (PS) dishes. Na ion implantation was performed at an energy of 50 keV with does ranging from 5᎒¹⁵ to 1᎒¹⁷ ions/cm². RBS was carried out with 1.5-MeV He⁺-ion beams and a fluence of 60 7C. The depth distribution of Na atoms showed a Gaussian distribution for the low dose. The profile is in a good agreement with a theoretical distribution calculated by a TRIM code. At the intermediate dose, the Na depth profile changed to a trapezoidal distribution. At the high dose, Na enrichment was found at the surface. Oxygen incorporation into PS is also observed. Na distribution behaviors in PS surface layer were discussed as a link to the O distribution.