The results of current–voltage (I–V) characteristics measured at different temperatures in polyethylene (PE) films obtained by our own experiments and the ones extracted from Suh K S et al (2000 J. Appl. Phys. 87 7333) are presented. The current depended strongly on temperature, namely, it increased with increase of temperature. The non-linearity in the I–V behaviour was observed at higher voltages. We suggest a phonon-assisted tunnelling model to explain the experimental results. The current mechanism in polymer diphenylaminostyrylbenzene (DASMB) films and in tris(8-hydroxyquinoline) aluminium (Alq3) films are also discussed.

Reverse current–temperature (IΓ/T) characteristics of Al–GaAs Schottky diodes with oxidized interfaces are measured in the temperature region of 250–400 K at various reverse bias voltage in order to elucidate a mechanism of carrier transport through the barrier. The IΓ/T dependencies are explained on the basis of phonon-assisted electrons tunneling from interface states to the semiconductor model. The barrier height, evaluated from the IΓ/T characteristics (activation energy) which depends on the applied voltage and temperature, is discussed. It is shown that these dependencies are due to the above-mentioned carrier transport through the Schottky barrier mechanism. The important of the phonon-assisted tunneling process on the current transport in the diodes is emphasized.

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Abstract:Electrical conduction in the temperature range of 120-370 K has been studied in sandwiched structures of Al/Ta 2 O 5 /Si. The tantalum oxide films were prepared by evaporation of tantalum on a p-Si crystal substrate, followed by oxidation at a temperature of 600˚C. The temperature-dependent current-voltage (I − V ) characteristics are explained on the basis of a phonon-assisted tunnelling model. The same explanation is given for I − V data measured on Ta 2 O 5 films by other investigators. From the comparison of experimental data with theory the density of states in the interface layer is derived and the electron-phonon interaction constant is assessed.

The current -voltage (I-V) characteristics in mica have been measured at different temperatures. The I-V characteristics possessed a temperature dependence, which was more clearly evident at lower fields. A comparison of the experimental results with the Frenkel thermo-emission theory and the theory of multiphonon-assisted tunnelling of charge carriers from the impurity centers, has been performed. It is shown that the experimental data better agree with the phonon-stimulated tunnelling theory than the Frenkel emission theory. Temperature-dependent I-V characteristics of М-SiO 2 -Si structures measured by Waters and Van Zeghbroeck [Appl. Phys. Lett. 76, 8, 1039 (2000)] are also reinterpreted in terms of the phonon-assisted tunnelling processes.