Synthesis and optical properties of chemical bath deposited ZnO thin film

• ZnO thin films were prepared by chemical bath technique.
• Band gap increases with decreasing the concentration of TEA (1 M−0.01 M).
• The optical band gap of the ZnO thin film was found in the range of 2.59–3.57 eV.

Zinc oxide thin films were deposited on glass slide from aqueous solution of ZnCl2 and NaOH by chemical bath deposition method. The films of various thicknesses have been obtained by varying the concentration of TEA (1 M−0.01 M). Optical properties, surface morphology and particle size of the deposited thin film have been studied by U.V spectrophotometer (Varian) SEM and XRD. The optical band gap of the ZnO thin film was found in the range of 2.59–3.57 ev. Optical constant is such as refractive index, extinction coefficient, real and imaginary parts of dielectric constant were evaluated from reflectance, transmittance and absorbance curve. The film show high transmittance in the visible/near infrared region. Reflectance (10%–20%), refractive index (2–2.6), extinction coefficient (0.04–0.075), real (4–7) and imaginary parts (0.2–.0.3) of dielectric constant are obtained in visible/near infrared region. SEM studies shown plate and powder like morphology of sample. Particles size is obtained in nano range.