Temperature dependent structural and optical properties of nanocrystalline CdO thin films deposited by sol-gel process

Nanocrystallites of cadmium oxide (CdO) thin films were deposited by sol-gel dip coating technique on glass and Si substrates. XRD and TEM diffraction patterns confirmed the nanocrystalline cubic CdO phase formation. TEM micrograph of the film revealed the manifestation of nano CdO phase with average particle size lying in the range 1.6-9.3 nm. UV-Vis spectrophotometric measurement showed high transparency (nearly 75% in the wavelength range 500-800 nm) of the film with a direct allowed bandgap lying in the range 2.86-3.69 eV. Particle size has also been calculated from the shift of bandgap with that of bulk value for the films for which the particles sizes are comparable to Bohr exitonic radius. The particle size increases with the increase in annealing temperature and also the intensity of XRD peaks increases which implies that better crystallinity takes place at higher temperature.