Oxygen vacancy-driven evolution of structural and electrical properties in SrFeO3-δ thin films and a method of stabilization

Epitaxial SrFeO_3-δ (SFO) thin films have been grown on various substrates by pulsed laser deposition. The structural and electrical properties of SFO thin films are monitored with time in different atmospheres at room temperature, showing time-dependent crystal structure and electrical conductivity. The increased out-of-plane lattice parameter and resistivity over time are associated with the increased oxygen vacancies density in SFO thin films. The epitaxial strain plays an important role in determining the initial resistivity, and the sample environment determines the trend of resistivity change over time. An amorphous Al₂O₃ passivation layer has been found to be effective in stabilizing the structure and electrical properties of SFO thin films. This work explores time dependent structure and properties variation in oxide films and provides a way to stabilize thin film materials that are sensitive to oxygen vacancies.