Structural and dielectric study of parylene C thin films

α , β, and γ relaxation mechanisms have been identified in semicrystalline (45% of crystallinity) parylene-C (–H2C–C6H3Cl–CH2–)n films. C–Cl bonds induce the β-relaxation and explain increase in the dielectric constant as the frequency decreases in usual temperatures of operation for devices incorporating parylene-C. At cryogenic temperature (<−20 °C), γ-relaxation is assigned to the local motions of phenyl groups. Both β and γ relaxation processes obey an Arrhenius law with activation energy Ea(β)=91.7 kJ/mole and Ea(γ)=8.68 kJ/mole. α-relaxation associated with cooperative segmental motions of the (–H2C–∅–CH2–)n chains is observed with a peak at 10−2 Hz for T=80 °C and follows a Vogel–Fulcher–Tamman–Hesse law.