Optical Properties of Polyimide Films Implanted with Ni + Ions

Transmission and refl ection spectra of polyimide fi lms 40-μm thick implanted with 40-keV Ni+ ions at fl uences 2.5·1016–1.5·1017 cm–2 and ion-beam current density 4, 8, and 12 μA/cm2 were studied in the range 200–1100 nm. It was shown that the optical transmission coeffi cient decreased smoothly after implantation as a result of light absorption and scattering in the modifi ed polymer layer containing nano-sized inclusions of C and Ni. The appearance of a broad refl ection band in the range 700–1100 nm in spectra from the implanted polymer and the reverse side of the polymer was due to a high Ni content in the implanted layer. The refractive index of the modifi ed implanted polymer layer that varied in the range 1.25–2.32 at 620 nm depending on the fl uence was determined by modeling the passage of light through the bilayer modifi ed layer/polymer matrix taking into account multiple refl ections at the interfaces.