Depth-resolved cathodoluminescence spectroscopy study of defects in $SrTiO3$

The authors report a depth-resolved cathodoluminescence spectroscopy study of defects and their distributions in $SrTiO3$ single crystals and epilayers. In $SrTiO3$ single crystals, the dominant defects are oxygen vacancies that locate mainly near the free surface, while Ti interstitials locate further into the bulk. Vacuum annealing increases the density of oxygen vacancies at $SrTiO3$ surfaces but reduces the density of Ti interstitials located deeper. In epilayers, the density and distribution of the defects depend on the film thickness and stoichiometry. The results reveal a strong dependence of $SrTiO3$ native point defects and their depth distributions on epitaxial growth and process conditions.