ZnO-Based Ultraviolet Photodetectors With Novel Nanosheet Structures

Abstract

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 τr = 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">*</sup> ) of the ZnO nanosheet photodetector were 6.12 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> W and 2.17 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> cm·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sup> W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , respectively.