Controllable preparation of ultrathin 2D BiOBr crystals for high-performance ultraviolet photodetector

Ternary layered compound materials (bismuth oxyhalides and metal phosphorus trichalcogenides) stand out in electronic and optoelectronic fields due to their interesting physical properties. However, few studies focus on the preparation of high-quality two-dimensional (2D) BiOBr crystals with a typical layered structure, let alone their optoelectronic applications. Here, for the first time, high-quality 2D BiOBr crystals with ultrathin thicknesses (less than 10 nm) and large domain sizes (similar to 100 mu m) were efficiently prepared via a modified space-confined chemical vapor deposition (SCCVD) method. It is demonstrated that a moderate amount of H2O molecules in the SCCVD system greatly promote the formation of high-quality 2D BiOBr crystals because of the strong polarity of H2O molecules. In addition, a linear relationship between the thickness of BiOBr nano sheets and Raman shift of A (1) mode was found. Corresponding theoretical calculations ig were carried out to verify the experimental data. Furthermore, the BiOBr-based photodetector was fabricated, exhibiting excellent performances with a responsivity of 12.4 A W-1 and a detectivity of 1.6x10(13) Jones at 365 nm. This study paves the way for controllable preparation of high-quality 2D BiOBr crystals and implies intriguing opportunities of them in optoelectronic applications.

Automated summary

Ternary layered compound materials, such as bismuth oxyhalides and metal phosphorus trichalcogenides, exhibit interesting physical properties in electronic and optoelectronic fields. In this study, high-quality 2D BiOBr crystals with ultrathin thicknesses and large domain sizes were efficiently prepared through a modified space-confined chemical vapor deposition method. The presence of H2O molecules greatly promotes the formation of high-quality 2D BiOBr crystals, and a linear relationship between the thickness of BiOBr nano sheets and Raman shift was observed. Moreover, the BiOBr-based photodetector showed excellent performances, indicating promising optoelectronic applications for 2D BiOBr crystals.