Visible Light Photodetectors Based on Multilayered Te-Doped Bi2o3nanoflakes with Ultrahigh Sensitivity

As quasi 2D semiconductors, bismuth oxychalcogenides (Bi 2 O 2 X, X = S, Se, Te) have recently attracted increasing attention due to their unique structure, exceptional air stability, and high electron mobility, which make them very promising candidates for the development of high-performance optoelectronic devices. Herein, multilayered Te-doped Bi 2 O 3 nanoflakes were obtained from a bulk single crystal via mechanical exfoliation method for the first time, and it exhibits an n-type semiconductor characteristics with a bandgap of 1.86 eV. The photodetectors based on the multilayered Te-doped Bi 2 O 3 were fabricated on a SiO 2 /Si substrate with van der Waals (vdW) bottom electrode contact geometry, which exhibit excellent photoresponse to visible wavelength. Under illumination with a 532 nm laser, the device showed ultrahigh photo-to-dark current ratio up to 2.16 × 10 4 , several orders of magnitude higher than previously reported 2D materials, as well as fast response speed (rise/decay time of 3.2/2.9 ms), high specific detectivity (9.85 × 10 12 Jones), which is favored by the ultralow dark current (∼30 fA). The high performance of Te-doped Bi 2 O 3 photodetector and its layered structure make it a promising candidate material for the application of low-dimensional optoelectronic devices