Electrical and NO2 sensing characteristics of Pd/ZnO nanoparticles based Schottky diode at room temperature

Abstract

The present work deals with Pd/ZnO nanoparticles based Schottky diode for detection of NO2 at room temperature (298 K). To fabricate Pd/ZnO Schottky diode, zinc oxide (ZnO) nanoparticles (NPs) based film was developed on glass substrate using sol-gel spin coating process. Subsequently; Pd was deposited on ZnO using thermal evaporation technique. The structural properties of developed ZnO film were studied using energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The particles size of the developed film was in range of ~25 to ~110 nm. The response of fabricated Pd/ZnO Schottky diode was studied upon exposure to NO2 in terms of change in I–V characteristics. The magnitude of barrier height and ideality factor has been evaluated with concentration of NO2 ranging from 10 to 50 ppm. The developed sensor has good sensitivity of ~45.2%, with fast response and recovery time; 67 s and 250 s respectively for 50 ppm concentration of NO2 with excellent repeatability. The obtained results have been explained in terms of surface and subsurface adsorption of NO2 on Pd, subsequently dissociation of NO2 and its diffusion, which creates dipole moment at the Pd/ZnO interface.