Crystallite growth and optical properties of cadmium oxide thin films annealed at various temperatures for various durations

The crystallite growth and optical properties of cadmium oxide (CdO) thin films annealed at various temperatures and for various durations have been investigated using grazing incident X-ray diffraction (GID), high-resolution transmittance electron microscopy (HR-TEM), selected area electron diffraction, and ultraviolet-visible spectrometry . All the thin films were annealed between 573 and 773 K for 10 to 60 min, respectively. GID results showed that all thin films contain only a single phase of CdO with (111) preferential orientation. The crystallite size of CdO increases with increases in annealing temperature and duration. It was found that the CdO crystallites followed a normal growth with an average activation energy of 13.04 ± 1.34 kJ/mol when annealed at 573–773 K for 10–60 min. The transmission spectra showed that the band gap energies of CdO thin films decreased from 2.474 to 2.050 eV as the annealing temperature increased, while the thin films maintained highly transparent in the visible spectral range.