Compositional, structural, and optical changes of polyimide implanted by 1.0Â MeV Ni+ ions

High energy Ni-ion implantation causes only a minor release of hydrogen and oxygen close to the polymer sub-surface region in about 60 nm thick layer penetrated by the ion beam; especially at ion fluencies below 1.0 × 1014 cm−2. The mostly pronounced structural changes of the Ni implanted PI were found for the samples implanted above ion fluence 1.0 × 1015 cm−2 and at the ion current density 7.2 nA/cm2, where the optical band gap significantly decreases and the reduction of more complex structural unit of PI monomer was observed.