Facile fabrication of heterostructure with p-BiOCl nanoflakes and n-ZnO thin film for UV photodetectors

Herein, high-quality n-ZnO film layer on c-sapphire and well-crystallized tetragonal p-BiOCl nanoflakes on Cu foil are prepared, respectively. According to the absorption spectra, the bandgaps of n-ZnO and p-BiOCl are confirmed as similar to 3.3 and similar to 3.5 eV, respectively. Subsequently, a p-BiOCl/n-ZnO heterostructural photodetector is constructed after a facile mechanical bonding and post annealing process. At -5 V bias, the photocurrent of the device under 350 nm irradiation is similar to 800 times higher than that in dark, which indicates its strong UV light response characteristic. However, the on/off ratio of In-ZnO-In photodetector is similar to 20 and the Cu-BiOCl-Cu photodetector depicts very weak UV light response. The heterostructure device also shows a short decay time of 0.95 s, which is much shorter than those of the devices fabricated from pure ZnO thin film and BiOCl nanoflakes. The p-BiOCl/n-ZnO heterojunction photodetector provides a promising pathway to multifunctional UV photodetectors with fast response, high signal-to-noise ratio, and high selectivity.

Automated summary

High-quality n-ZnO film and well-crystallized tetragonal p-BiOCl nanoflakes were successfully prepared in this study. A p-BiOCl/n-ZnO heterojunction photodetector was constructed with strong UV light response, but the on/off ratio was lower compared to devices made from pure ZnO thin film and BiOCl nanoflakes. The heterostructure device also exhibited a shorter decay time.