ZnO-based ultraviolet photodetectors with novel nanosheet structures

This study presents the fabrication of ZnO nanosheets on a glass substrate using a room-temperature (approximately 25 °C) solution method. The average length and diameter of the ZnO nanosheets were 1.2 μm and approximately 5 nm, respectively. The ultraviolet (UV)-to-visible rejection ratio of the sample is approximately 42 when biased at 1 V, and the fabricated UV photodetector is visible-blind with a sharp cutoff at 370 nm. The transient time constants measured during the rise time and fall time were τ r = 5.37 s and 6.02 s, respectively. The low-frequency noise spectra obtained from the UV photodetector were caused purely by the 1/ f noise. The noise-equivalent power and normalized detectivity (D*) of the ZnO nanosheet photodetector were 6.12 × 10 ^-9W and 2.17 × 10 ⁹ cm·Hz^0.5 W ^-1, respectively.