OXIDATION OF POLYETHYLENE IMPLANTED WITH AS IONS TO DIFFERENT EXTENTS

Polyethylene (PE) samples implanted with 150 keV As+ ions to the exten ts of 5 X 10(13)-1 X 10(15) cm-2 were studied using a standard RBS (Ru therford Back Scattering) technique. The measured projected range of A s+ ions (R(P) = 120 +/- 20 nm) is significantly lower than theoretical range of 170 nm calculated using TRIM code for pristine PE, the diffe rence probably being due to structural changes in PE resulting from th e ion implantation. The measured range straggling DELTAR(P) = 60 +/- 1 0 nm also exceeds the theoretical TRIM value of 33 nm. The profile bro adening might be due to the diffusion of the As atoms through the dama ged surface layer of PE. Noticeable oxidation of the implanted samples was also observed, with most of the oxygen atoms trapped in the regio n of maximum radiation defects. The total oxygen content in the sample surface layer and its depth concentration profile depend on the exten t of implanted ions. For the highest implanted dose of 1 x 10(15) cm-2 , the oxygen depth profile exhibits two distinct concentration maxima, the first on the sample surface and the second at a depth close to th e expected range of 150 keV As+ ions.