Improved visible-light-dielectric response in self-doped rutile TiO2

Due to the observed photo dielectric effect (PDE), oxide semiconductors have enormous potential in the development of optoelectronic devices. In this work, self doped titanium dioxide was prepared by solid-state reaction method, and its bandgap was reduced, which is conducive to fully utilizing the visible light band. There are three relaxations from 77 K to 300 K, resulting in a larger dielectric constant in the high-temperature region. After light irradiation, the dielectric constant (ε`) and dielectric loss (tanδ) increase, and the PDEs increase with the increase of photon energy. By designing the interface of different metal electrodes, the PDE of visible light has been greatly improved. Especially, it was found that the PDE of the sample with one electrode in ohmic contact and one electrode in Schottky contact was the most significant, with a maximum of 24.1 %. Samples with Schottky contacts will exhibit a special frequency range of abnormal changes in resistivity in the high-frequency Maxwell Wagner region affected by non-electrode effects. This resistance change will be amplified by illumination, and the Debye peak will shift towards higher frequencies after illumination. The higher the energy, the greater the shift.