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The defect chemistry in the mid-band gap semiconductor SrTiO3 (STO) plays a crucial role for its properties. These can be tuned by temperature, doping, p(O2), and UV irradiation. Since UV exposure leads to the formation of photoelectrons and –holes the oxygen chemical potential of oxygen is changed. This results in an enhanced incorporation of oxygen into Fe-doped STO at elevated temperatures. In this work different approaches to investigate this phenomena are introduced. i) Oxygen compositional changes can be probed by measuring the light induced weight change using GaPO4 microbalances. ii) UV exposure and oxygen incorporation also cause a photo and a battery voltage, which can be measured in-situ. iii) Inplane conductivity measurements reveal an increase of the electron hole conductivity, as the result of Fe3+ oxidation to Fe4+. iv) This change of the Fe oxidation state additionally leads to a change in the color of Fe-doped STO from brownish/transparent to black. Two broad additional absorption bands in the region of 440 nm and 590 nm occur.

Wide band gap semi-conductors such as SrTiO3 (STO) have attracted high interest for photoelectrochemical water splitting and as part of high temperature photovoltaic cells. However, the impact of UV irradiation on the composition (e.g. the oxygen content) of STO and Fe doped STO (Fe:STO) at elevated temperatures has hardly been studied. In Fe:STO, UV exposure causes an enhanced oxygen incorporation rate and, therefore, a decreased oxygen vacancy concentration in air at elevated temperatures. In this contribution we discuss such bulk stoichiometric changes in terms of optical and electrochemical (e.g. AC conductivity) properties. Moreover, the kinetics behind the incorporation were examined, more precisely chemical diffusion coefficients obtained from UV/VIS measurements were calculated.

Wide band gap semi-conductors such as SrTiO3 (STO) have attracted high interest for photoelectrochemical water splitting and as part of high temperature photovoltaic cells. However, the impact of UV irradiation on the composition (e.g. the oxygen content) of STO and Fe doped STO (Fe:STO) at elevated temperatures has hardly been studied. In Fe:STO, UV exposure causes an enhanced oxygen incorporation rate and, therefore, a decreased oxygen vacancy concentration in air at elevated temperatures. In this contribution we discuss such bulk stoichiometric changes in terms of optical and electrochemical (e.g. AC conductivity) properties. Moreover, the kinetics behind the incorporation were examined, more precisely chemical diffusion coefficients obtained from UV/VIS measurements were calculated.