UV-light enhanced high sensitive hydrogen (H2) sensor based on spherical Au nanoparticles on ZnO nano-structured thin films

Abstract

In this paper, using RF magnetron sputtering, we first demonstrate a UV-light enhanced high sensitive hydrogen sensor based on spherical Au nanoparticles on ZnO nano-structured thin films. The response of the sensor is highly dependent on UV light illumination. In the sensor, nano-structured thin films of Au/ZnO have been synthesized by RF magnetron sputtering on pre-interdigitated alumina substrates. The spherical Au nanoparticles have been successfully formed on the surface of the ZnO film by varying/controlling the post-annealing temperature (600 °C) and environment (N2). The thin films have been systematically characterized by XRD, SEM, Raman, and XPS. As revealed by the Hydrogen gas sensing results, the N2 post-annealed Au/ZnO thin film sensor has remarkably enhanced the sensing performance under UV light illumination of about 172% at 1000 ppm of H2 concentration-two, times higher than when it was without UV light (80%). The gas sensor under UV light lowers the gas detection limit to 50 ppm from 100 ppm (without UV light). We discuss the detailed mechanism of the gas sensor under dark and UV light with the help of different theoretical models such as spillover and band bending mechanism.