Structural, morphological, optical and gas sensing properties of nanocrystalline ceria thin films

Ceria thin films are deposited with varying oxygen pressures (1- 225 m torr) and at an optimized substrate temperature of 1023K on quartz substrates by pulsed laser deposition technique. X-ray diffraction studies indicated that the prepared thin films are polycrystalline in nature. The prepared thin films contain nano crystals of size in the range of 20-31nm. Crystallite size, strain and dislocation densities of the ceria thin films have been calculated. To know the preferred orientation of the films texture coefficient has been calculated. The characteristic Raman peak appeared at 463 cm-1 is associated with F2g active mode confirm the cubic fluorite structure of ceria. Surface morphology of the thin films carried out by atomic force microscopy. The optical properties of the thin films are investigated by using UV-Vis spectroscopy technique in the wavelength range 200-800nm.The optical band gap, refractive index and absorption coefficient are calculated. Gas sensing characterization of ceria thin films have been carried out by chemiresistive method for various concentrations of acetone vapour and operating temperatures.