Effect of ion implantation doping on electrical properties of yttria-stabilized zirconia thin films

The change in conductivity of Fe and Ti implanted rf-sputtered layers of yttria-stabilized zirconia (YSZ) was studied as a function of the temperature (400–800°C) and oxygen partial pressure. In an oxidized state and in the temperature range of 400–600°C, the conductivity of the Fe implanted YSZ film (15keV, 8×1016 at.cm−2) was dominated by the n-type electronic conductivity of a thin Fe2O3 layer with an estimated thickness of less than 2 nm on top of the YSZ thin film. Due to the incorporation of a part of the implanted Fe atoms in the yttria-stabilized zirconia lattice, the ionic conductivity was somewhat decreased. In a reducing atmosphere this electronic conduction was no longer observed. In an oxidized state, the conductivity of the YSZ film was not influenced by the implantation of Ti (15keV, 8×1016at.cm−2). After reduction in a H2 atmosphere, an increase in the conductivity of the sputtered film with 2–3 orders of magnitude was observed. This has been ascribed to the presence of nonstoichiometric TiO2−x, which is an semiconductor.