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

超薄二维BiOBr晶体的可控制备及其紫外光电探测应用

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(~100μm)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 nanosheets and Raman shift of A1g(1)mode was found.Corresponding theoretical calculations 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 1.6×1013 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.

本文采用空间限域化学气相沉积方法(SCCVD)成功制备出厚度低于10 nm,横向尺寸达100μm的高质量二维BiOBr单晶纳米片.实验结果表明,在SCCVD系统中引入适量的水汽可有效促进二维BiOBr晶体的形成.实验测试和理论计算相结合,分析了二维BiOBr的拉曼光谱随厚度的变化规律.基于该二维BiOBr晶体的光电探测器性能出色,对365 nm的紫外光响应度达到了12.4 A W-1,可探测度达1.6×1013Jones.本文为大尺寸二维BiOBr晶体的可控制备提供了研究思路,同时探索了其在光电探测领域的应用.