Self-powered visible-blind ultraviolet photodetectors based on SnO₂ nanowire cotton synthesized using thermal chemical vapor deposition

We report a simple method for fabricating a SnO₂ nanowire (NW) cotton-based ultraviolet (UV) photodetector. SnO₂ NW cotton was synthesized by thermal chemical vapor deposition with SnO powder. Ag paste was coated onto the surface of the SnO₂ NW cotton to serve as the electrode. The performance of the photodetector was evaluated upon UV light exposure at a wavelength of 254 nm, with a photo-to-dark-current ratio of 7.9 × 10⁵, photoresponsivity of 1.141 × 10³ A/W, and specific detectivity of 9.0 × 10¹⁵ Jones. The spectral photoresponsivity was also determined in the 200–600 nm wavelength range. The results showed a maximum responsivity at 270 nm and a cutoff edge wavelength of 360 nm, exhibiting the characteristics of a visible-blind UV photodetector. In addition, self-powered capability with a photocurrent of 2.3 nA was demonstrated at a nominal zero bias.