Photoresponse and decay mechanism of an individual ZnO nanowire UV sensor

摘要

UV sensor based on an individual ZnO nanowire (NW) was fabricated by micro-grid template method. The photo-electric properties of the sensor were investigated under the illumination of He-Cd laser (325 nm). The current-voltage (I-V) characteristics are linear and the resistivity of the ZnO NWs is calculated to be 1.7 Ω cm in dark and 0.2 Ω cm under UV illumination. The decay process, after the illumination is off, exhibits a third-order exponential decay function, with time constants of τ _1 = 0.2 s, τ _2 = 8.5 s and τ _3 = 86.6 s. It can be attributed to the electron-hole recombination, and the readsorption of vaporized water and oxygen molecules.