Regulation of the electron concentration distribution in TiO2/BaTiO3 photodetector

TiO2 film ultraviolet photodetectors (UVPDs) always suffered from high dark current and low on-off ratio, which have been studied by many works. To improve the performance of the UVPDs based on TiO2, we fabricated a UVPD based on TiO2 with self-polarized BaTiO3 (SPBTO) through a spin-coating method. Compared with the dark current (1.12 nA) and on-off ratio (1.15 x 103) of the single TiO2 film UVPD, that of TiO2-SPBTO film UVPD are 1.27 x 10-1 nA and 1.17 x 104, respectively. The result shows that TiO2-SPBTO has better photoelectric detection capabilities, which may be due to the modulating the electronic distribution of TiO2 films by SPBTO film. To explore the mechanism of the device, we analyzed the carrier distribution within the heterojunction by finite element analysis, which demonstrated that the SPBTO film modulates the electron concentration distribution of TiO2 film, resulting in a lower dark current and a higher on-off ratio. This work provides a potential candidate for high-performance UVPDs.