Enhanced Gas Sensing Properties of Spin-coated Na-doped ZnO Nanostructured Films

Mohamed A Basyooni; Mohamed Shaban; Adel M El Sayed

doi:10.1038/srep41716

Enhanced Gas Sensing Properties of Spin-coated Na-doped ZnO Nanostructured Films

Sci Rep. 2017 Feb 1:7:41716. doi: 10.1038/srep41716.

Authors

Mohamed A Basyooni^{1

2}, Mohamed Shaban¹, Adel M El Sayed³

Affiliations

¹ Nanophotonics and Applications (NPA) Lab, Department of Physics, Faculty of Science, Beni- Suef University, Beni- Suef 62514, Egypt.
² Space Research Lab, Solar and Space Research Department, National Research Institute of Astronomy and Geophysics (NRIAG), Helwan, Cairo, Egypt.
³ Department of Physics, Faculty of Science, Fayoum University, Fayoum 63514, Egypt.

Abstract

In this report, the structures, morphologies, optical, electrical and gas sensing properties of ZnO and ZnO: Na spin-coated films are studied. X-ray diffraction (XRD) results reveal that the films are of a single phase wurtzite ZnO with a preferential orientation along (002) direction parallel to c-axis. Na doping reduces the crystalline quality of the films. The plane surface of ZnO film turned to be wrinkle net-work structure after doping. The reflectance and the optical band gap of the ZnO film decreased after Na doping. The wrinkle net-work nanostructured Na-doped film shows an unusually sensitivity, 81.9% @ 50 sccm, for CO₂ gas at room temperature compared to 1.0% for the pure ZnO film. The signals to noise ratio (SNR) and detection limit of Na-doped ZnO sensor are 0.24 and 0.42 sccm, respectively. These enhanced sensing properties are ascribed to high surface-to-volume ratio, hoping effect, and the increase of O- vacancies density according to Kroger VinK effect. The response time increased from 179 to 240 s by the incorporation of Na atoms @50 sccm. This response time increased as the CO₂ concentration increased. The recovery time is increased from 122 to 472 s by the incorporation of Na atoms @50 sccm.