Structural and optical properties of ZnO nanocrystals growth by the chemical bath deposition

ZnO films prepared on glass substrates at T = 80 °C ± 3 °C using the chemical bath deposition technical. The precursor solutions was KOH (0.5 M), NH4NO3 (1.5 M) using three different Zn(NO3)2 (0.2 M, 0.3 M, 0.4 M) concentration. The morphology is investigated by Scanning Electron Microscopy (SEM) and images shows porous matrix with cavities of different size, javelin and tretrap. According to the XRD diffractograms, all the nanocrystals present hexagonal crystalline phase with grain size of ∼33.4 nm, ∼36.5 nm and ∼34.2 nm. The samples present typical stress in these films. Absorbance spectrum exhibits a characteristic band of the nanocrystals, band gap energy shows a shift in the range ∼3.7-3.8 eV associated with decreasing grain size, as well as the quantum confinement effect in this case of nanocrystalline material. Photoluminescence shows bands, associated with the existence of interstices and vacancies of oxygen and Zinc respectively. Analysis of chemical reactions is performed using the Nernst equation to quantify changes ΔG° to predict the spontaneity of the reactions.