Frequency dependence of dielectric loss in thin aromatic polyimide films

The dielectric response of thin aromatic polyimide films with thicknesses ranging from 400 to 3×104 has been measured in the frequency range 104-109 Hz. The results show the presence of two components of dielectric polarization. One of these components exhibits a frequency dependence of the ''universal'' type ωn-1 with n=1.0 within experimental error, independent of film thickness, and is attributed to hopping electrons generated from excitation of a charge-transfer complex, followed by charge separation. The other component is characterized by a very low dielectric loss and is attributed to the π-electron response of the dielectric lattice. The results indicate that film morphology plays an important role in determining the magnitude of the dielectric loss in the films, but does not affect its frequency dependence. © 1993 The American Physical Society.