Modeling the charge transport mechanism in amorphous Al2O3 with multiphonon trap ionization effect

The charge transport mechanism in amorphous alumina, Al2O3, is investigated both theoretically and experimentally. We found that the experimental current–field–temperature dependencies can hardly be understood based on the commonly used Frenkel effect or the thermally-assisted tunneling model. Instead, we suggest that the charge transport in Al2O3 is related to the ionization of the deep trap by multiphonon tunneling. Excellent agreements between the predicted, the measured data were obtained by using the proposed multiphoton model with the following values of trapping parameters: thermal ionization energy of 1.5 eV, optical ionization energy of 3.0 eV, phonon energy of 0.05 eV, electron effective mass of 0.4me. The density of electron trap and electron capture cross-section of neutral traps are 2 × 1020 cm−3 and 5 × 10−15 cm2, respectively.