Study on doping effect of Sn doped ZnO thin films for gas sensing application

Abstract

Tin doped ZnO (Sn:ZnO) thin films were deposited onto glass substrate using sol-gel spin coating method. The doping concentrations of thin films were varied from 1.0 – 5.0 at. % Tin. The optical and electrical properties of Sn doped ZnO thin films were investigated. The electrical properties were analyzed using I–V measurement (CEP 2400). The optical properties were characterized by ultraviolet visible (UV-VIS-NIR) spectrophotometer. Gold (Au) was used as a metal contact using electron beam thermal evaporator (ULVAC). The electrical properties show that the Sn:ZnO thin films exhibit Ohmic behavior with Au metal contact. The highest resistivity of Sn doped ZnO thin films found to be 3.17 × 103 Ωcm. And then, the conductivity of the thin films found to be 1.88 × 10−4 Scm-1 for 2.0 at.% doping concentration. The highest porosity of Tin doped ZnO thin film was found 47% at 3.0 at. % Tin. The highest gas response was found 2.53 in the concentration of Nitrogen gas with flowrate 220mL/min at room temperature. The effect of Tin doping concentration of the ZnO thin films for gas sensing application at room temperature will be extensively discussed in this paper.