Zinc oxide (ZnO) thin films were sol-gel spin coated on glass substrates and annealed at various temperatures from 300–500 °C. Zinc acetate dihydrate (ZAD), monoethanolamine (MEA), and 2-methoxyethanol were used as the starting materials, stabilizer and solvent, respectively. The effect of annealing temperature on the structural and optical properties of the ZnO thin films was investigated by X-ray diffractometer (XRD), atomic force microscope (AFM), UV–VIS spectrophotometry and ellipsometry. The XRD results showed the films to have a preferential c-axis orientation, whereas the AFM results confirmed a columnar structure. The surface roughness increased with the increase in annealing temperature. Parameters such as ratio of free charge carrier concentration to effective mass (N/m*) and plasma frequency (ωp) were determined from the transmittance graph using the Wemple di Domenico model. Both N/m* and ωp were noticed to reduce with the increase in annealing temperature. Band gap decreased with the increase in the annealing temperature indicating absorption edge shift towards the red region.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Materials Chemistry