The impact of UV light (λ = 365 nm) on defect chemistry and composition of undoped SrTiO₃ single crystals was investigated by means of impedance spectroscopy. In-plane conductivity measurements between 280 and 450 °C in air reveal a drastic increase of the bulk conductivity upon UV illumination. The measured time dependence of this increase is in accordance with oxygen chemical diffusion in SrTiO₃. The corresponding photo-induced change in defect concentrations is caused by oxygen being pumped from the gas phase into the oxide under UV irradiation. This affects the entire SrTiO₃ crystal rather than only the thin UV absorption zone and leads to very high oxygen chemical potentials with nominal oxygen pressures up to 10⁶ bar. After switching the UV light off, the resulting conductivity increase relaxes extremely slowly due to slow surface exchange kinetics. A mechanistic model is introduced to explain the impact of UV light on the oxygen chemical potential as well as on the oxygen vacancy and hole/electron concentrations in semiconducting oxides, here SrTiO₃. This model is based on the formation of oxygen quasi-chemical potentials in the illuminated region. It is discussed how the interplay of four kinetic parameters causes the observed time-dependent stoichiometry and thus conductivity changes.

通过阻抗谱研究了紫外光（λ = 365 nm）对未掺杂SrTiO ₃单晶的缺陷化学和组成的影响。在空气中 280 至 450 °C 之间的平面内电导率测量表明，在紫外线照射下体积电导率急剧增加。测量的这种增加的时间依赖性与 SrTiO ₃中的氧化学扩散一致。缺陷浓度的相应光致变化是由在紫外线照射下将氧气从气相泵入氧化物中引起的。这会影响整个 SrTiO ₃晶体，而不仅仅是薄的紫外吸收区，并导致非常高的氧化学势，标称氧压高达 10 ⁶ 酒吧。关闭紫外光后，由于缓慢的表面交换动力学，由此产生的电导率增加非常缓慢。引入了一个机械模型来解释紫外光对氧化学势以及半导体氧化物（此处为 SrTiO ₃ ）中的氧空位和空穴/电子浓度的影响。该模型基于光照区域中氧准化学势的形成。讨论了四个动力学参数的相互作用如何导致观察到的随时间变化的化学计量，从而导致电导率变化。