Electronic properties of defects in SrTiO3 - theory and experiments

SrTiO3 is a commercially available wafer material e.g. for the integration of oxide superconductors or microwave filter applications. The electric properties of SrTiO3 are routinely modified by doping with additional elements such as Nb. A targeted defect engineering may, however, achieve similar or superior results, while remaining in the ternary system (Sr,Ti,O), i.e. without the need for extrinsic doping. Material characterization methods able to distinguish such defects in particular are needed. In the present study we combine all-electron first-principles calculations with electron energy loss and X-ray absorption spectroscopy to study the electronic properties of SrTiO3-related oxygen deficient compounds. In particular, such changes of the SrTiO3 core-level spectra are studied, which occur if O vacancies accumulate in SrTiO3, or if excess SrO(001) planes are inserted to form Ruddlesden-Popper-type compounds.