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

Abstract

The ion irradiation leads to deep structural and compositional changes in the irradiated polymers. Ni+ ions implanted polymers were investigated from the structural and compositional changes point of view and their optical properties were investigated. Polyimide (PI) foils were implanted with 1.0MeV Ni+ ions at room temperature with fluencies of 1.0×1013–1.0×1015cm−2 and two different ion implantation currents densities (3.5 and 7.2nA/cm2). Rutherford Back-Scattering (RBS) and Elastic Recoil Detection Analysis (ERDA) were used for determination of oxygen and hydrogen escape in implanted PI. Atomic Force Microscopy (AFM) was used to follow surface roughness modification after the ion implantation and UV–Vis spectroscopy was employed to check the optical properties of the implanted PI. The implanted PI structural changes were analysed using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR).High energy Ni-ion implantation causes only a minor release of hydrogen and oxygen close to the polymer sub-surface region in about 60nm thick layer penetrated by the ion beam; especially at ion fluencies below 1.0×1014cm−2. The mostly pronounced structural changes of the Ni implanted PI were found for the samples implanted above ion fluence 1.0×1015cm−2 and at the ion current density 7.2nA/cm2, where the optical band gap significantly decreases and the reduction of more complex structural unit of PI monomer was observed.