Boosting of CO2 sensitivity in Zn-doped SnO2 thin film: Analysis based on structural, optical and dielectric characterization

Abstract

Zn-incorporated SnO2 thin films are deposited by spray pyrolysis technique from an ethanolic solution of SnCl4·5H2O at 310 °C. The structural analysis shows that both undoped and Zn-doped films are tetragonal rutile structures with crystallite sizes ranging from 44 to 35 nm. Morphological analysis shows that the particles are spherical in shape and uniformly distributed. The UV–Vis absorbance spectra of the samples are recorded and the band gap energies are estimated. The CO2 sensing properties are investigated in detail. The dielectric constant is found to vary with frequency that is attributed to the multi-relaxation time constant of the energy states responsible for the conduction mechanism. The AC conductivity has been found to obey a power law, indicating a multi-hopping conduction mechanism in the samples. These results are discussed in relation to the sensing characteristics of the sample.