The current density was measured as a function of time in thin (less than 100nm) capacitors with Pt electrodes. The current density curve exhibited a peak ahead of the onset of resistance degradation. The peak position on the time axis varied with the applied voltage and temperature. The data were explained in terms of space-charge limited current transients, and the measured current was identified as being an ionic current which was associated with O vacancies. By means of space-charge limitation analysis, the mobility of the O vacancies was measured as a function of temperature. The mobility, as deduced from current measurements, was shown to be compatible with the Einstein relationship for mobility and diffusivity. The ionic current that was associated with O vacancies was shown to be an important component of the measured current in these samples.

S.Zafar, R.E.Jones, B.Jiang, B.White, P.Chu, D.Taylor, S.Gillespie: Applied Physics Letters, 1998, 73[2], 175-7