Thin films were deposited by means of vacuum evaporation. The conductivity and activation energy were found to be thickness-dependent for films of up to 500nm. Conductivity occurred via anionic defect motion, with an activation energy of 0.32eV, and the ionic transference number was equal to 0.995 at room temperature.

T.A.Kuku: Thin Solid Films, 1999, 340[1-2], 292-6