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 X 10(4) angstrom has been measured in the frequency range 10(4)-10(9) Hz. The results show the presence of two components of dielectric polarization. One of these components exhibits a frequency dependence of the ''universal'' type omega(n-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 pi-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.