Self-Polarized BaTiO3 for Greatly Enhanced Performance of ZnO UV Photodetector by Regulating the Distribution of Electron Concentration

ZnO film ultraviolet photodetectors (UV PDs) have always suffered from slow speed and low photosensitivity that restrict their broader applications. To break through those barriers, high-performance ZnO UV PD based on self-polarized BaTiO3 (BTO) is first introduced through a facile one-step spin-coating method. Compared with pure ZnO film UV PD with low on/off ratio (65) and slow speed (4.1/7.5 s) at 3 V bias under 350 nm UV light, the BTO-ZnO bilayer film device exhibits an ultrahigh on/off ratio (14 300) and ultrafast response speed (0.11/5.80 ms), which is much faster than that of the most reported ZnO film-based UV PDs. The numerical simulation demonstrates that the spatial distribution of electron concentration of ZnO film is regulated by the self-polarization of BTO film, resulting in low dark current and fast response time of the BTO-ZnO PD. This work provides a new approach to fabricate high-performance PDs based on self-polarized ferroelectric materials.