Tunable Gas Sensing Properties of ZnO Thin Films through Layer Engineering: Structural, Morphological, and Optical Analysis

Rajni Kant  Verma; Ashok  Jangid; Ranjit  Kumar

doi:10.69968/ijisem.2025v4i2230-237

Authors

Rajni Kant Verma Department of Physics and Computer Science, Dayalbagh Educational Institute, (Deemed to be University), Dayalbagh, Agra.
Ashok Jangid Department of Physics and Computer Science, Dayalbagh Educational Institute, (Deemed to be University), Dayalbagh, Agra.
Ranjit Kumar Department of Chemistry, Dayalbagh Educational Institute, (Deemed to be University), Dayalbagh, Agra.

DOI:

https://doi.org/10.69968/ijisem.2025v4i2230-237

Keywords:

Multilayer, Semiconductor, Gas Sensing, ZnO, XRD, FESEM, UV-vis

Abstract

The sol-gel method was employed to effectively "synthesise multilayer ZnO thin films with 3, 5, and 7 layers". The films were characterised for their optical, compositional, morphological, and structural properties. The crystalline quality was enhanced, as evidenced by the decrease in dislocation density and the increase in crystallite size as the number of layers increased, as confirmed by X-ray diffraction (XRD) and "the hexagonal wurtzite structure with a preferential (002) orientation". Field Emission Scanning Electron Microscopy (FESEM) revealed uniform and granular surface morphology, consistent across all layers, with particle size increasing slightly in thicker films. Energy Dispersive Spectroscopy (EDS) validated nearly stoichiometric Zn and O composition, with no significant variation due to the number of layers, indicating high purity. UV-Vis spectroscopy demonstrated strong UV absorption and excellent transparency in the visible region, with optical bandgap values of 2.66 eV, 2.80 eV and 2.81 eV for 3, 5 and 7 layers, respectively, suggesting improved optical properties in thicker films. The results confirm the suitability of these films for optoelectronic, UV-sensing, and photocatalytic applications, with tunable properties enabled by varying the number of layers. This study underscores the reliability of the sol-gel method for fabricating high-quality multilayer ZnO thin films.

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