Dielectric properties of gold-containing plasma-polymerized thin films

Abstract

Electrical properties of gold-containing plasma-polymerized thin films have been studied in the dielectric regime (isolated conducting clusters dispersed in a polymeric matrix). dc measurements over a wide temperature range provide evidence for a transport process involving the matrix itself as opposed to tunneling directly across the insulating barrier between metallic clusters. The films display space-charge-limited conduction which is due to the existence of trap states in the polymeric phase. An exponential distribution of traps with a peak value of the order of 1017 cm−3 eV−1 has been deduced from the voltage-current data. The ac behavior is dominated by conduction losses at low frequency with a dissipation peak due to interfacial polarization between metal and matrix in the kHz range. Another relaxation is found for gold-rich films. The full interpretation requires more details on the polymeric phase which composition and electrical properties change gradually with an increasing gold concentration.