In-plane dominated growth strategy of 2D Bi2O2Se nanosheets and photodetectors performance

Two-dimensional (2D) semiconductor Bi 2 O 2 Se shows considerable promise for optoelectronic devices owing to its high carrier mobility, tunable bandgap, and excellent air stability. However, inability of conventional methods to precisely control nanosheets orientation compromises the resulting nanosheets quality and thickness uniformity. To address the issues of growth orientation and thickness in Bi 2 O 2 Se nanosheets, this work achieved the synthesis of large-area, high-quality Bi 2 O 2 Se through optimization of the source-substrate distance and pressure, combined with exploration of the corresponding growth mechanism, and constructed optoelectronic detection devices. Research into the influence of Bi 2 O 2 Se nanosheets thickness on device photoresponse characteristics indicates that at 18 nm thickness, under excitation by 420 nm wavelength light, the corresponding optimal responsivity and high detectivity reached ∼3269 A/W and 4.25 × 10 10 Jones respectively, with an external quantum efficiency as high as 6.2 × 10 5 %. Moreover, the photoconductive effect mechanism of Bi 2 O 2 Se-based photodetectors devices has been preliminarily explored, facilitating further optimization of photodetectors device development for 2D materials.