Oxygen sensitivity of perovskite-type dielectric thin films

We have considered perovskite-type dielectric materials as promising candidates for use as highly sensitive oxygen sensors because of the indispensable interaction between ionic polarization in perovskites and adsorbed oxygen on the perovskite surface. In this study, a gas calibration system equipped with a ZrO2-based oxygen pump (SIOC-200C, STLAB, Japan) was used. Among the materials studied, Cr:SrTiO3 shows sufficient sensitivity to detect residual oxygen in helium ambient at ppb levels. In contrast to Cr:SrTiO3, Cr:BaTiO3 shows no oxygen sensitivity. The merits of Cr:SrTiO3 might be attributed to the coexistence of large and small polarons. Perovskite-based sensor is expected to provide a solution for real-time monitoring of residual oxygen during semiconductor manufacturing.