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

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.