Implantation-Induced Conductivity of Polymers

ABSTRACTIon implantation causes an increase by ~14 orders of magnitude in the electricalconductivity of normally insulating polymers such as polyacrylonitrile (PAN), poly(2,6 dimethyl phenylene-oxide) (PPO), and poly (pphenylene sulfide) (PPS), after ion implantation with Br at fluences of 3 × 1015 ions/cm2. The temperature dependence of the dc conductivity was measured in the range 23 〈 T 〈 293 K and results show an exponential law σ ~ exp(−To/T)a) for PAN, PPO and PPS with α =1/2, suggesting a one-dimensional hopping mechanism. The temperature dependence of the thermoelectric power (TEP) identifies the sign of the dominant carrier type. The TEP exhibits linear metallic behavior, with small magnitudes (~3μV/K), and shows Br implantation to yield p-type material in PPS and n-type material in PAN with extremely low values of mobility (〈 10−3 cm2/V sec) and correspondingly very high values of the carrier concentration estimated to be 5 × 1022 cm-3. Results are also reported for the frequency dependence of the AC conductivity and of similarly implanted PPS and PAN samples.