Modification of polyethylene properties by implantation with F+ ions and iodination

✍ Scribed by O. Jankovskij; V. Švorčík; V. Rybka; V. Hnatowicz

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 418 KB
• Volume: 60
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960531)60:9<1455::aid-app20>3.0.co;2-#

✦ Synopsis

Polyethylene samples implanted with 150 keV F+ ions to the doses 1011-1015 cm-' were doped with iodine by exposing them to iodine vapors a t 90°C for 3 h. The iodine depth profiles, measured by Rutherford back-scattering techniques, evolve dramatically with increasing implanted doses, from "bumpy" profiles at lower fluences to a "depleted" one comprising two concentration maxima with no iodine in between observed at highest dose. The areal density of iodine incorporated into the 500-nm-thick surface layer is proportional to the ion dose for the doses I 1 X 1013 cm-' and it achieves a saturation or declines at higher doses. The results support the concept of enhanced iodine diffusion in the radiationdamaged surface layer and its trapping on the radiation defects within. The sheet resistivity of as-implanted PE is practically constant, independent of the implanted dose. Iodine doping of the ion-implanted PE samples results in immediate, strong decrease of the sheet resistivity by 3-4 orders of magnitude which, however, is not stable. The measured temperature dependence of the sheet resistance indicates p-semiconducting character of ionimplanted and iodinated samples at the temperatures below the PE melting point. The iodine redistribution and/or escape with increasing temperature is observed.