Optical and electrical properties of polycarbonate layers implanted by high energy Cu ions

1 MeV copper ions were implanted in polycarbonate (PC) matrices with fluences ranging from 5 × 1013 ions cm-2 to 1 × 1017 ions cm-2 in order to modify the optical and electrical properties of the polymer host. Increasing the ion fluence, an increase of the overall absorption and a redshift of the optical band gap were observed, from the initial value of 3.40 eV for the pristine PC to 0.80 eV measured for 1 × 1017 ions cm-2. For fluences above 5 × 1014 ions cm-2 a broad optical absorption bands at 450-475 nm and 520 nm were observed and, from 1 × 1016 ions cm-2, an additional band appeared at 570 nm. Both bands redshift when the fluence is increased. On the contrary, the optical response of the highest fluence sample is characterized by an overall band at 580 nm. The chemical modifications observed in the polymer ranges from induced -OH stretching, CO and -CC- double bonds and -CC and CH triple bonds formation, as the ion fluence increases. The implantation process affects the electrical properties of the polymer inducing a strong reduction in sheet resistance when ion fluence exceeds 5 × 1016 ions cm-2. A value of ∼7.1 × 107 Ω/sq has been obtained for the highest fluence, i.e. about 10 order of magnitude lower than the pristine PC.