Changes in the structural and optical properties of CeO_2 nanocrystalline films: Effect of film thickness

摘要

In this paper, nanocrystalline cerium dioxide (CeO_2) thin films with thicknesses of 41-334nm were grown on glass substrates at 450 deg C by pulsed spray-evaporation chemical vapor deposition (PSE-CVD). Through changing the film thickness, the texture and the band gap energy of CeO_2 were altered in a wide range, which implies promising applications in microelectronics, optoelectronics and photocataly-sis. X-ray diffraction (XRD) shows that all films grown by this process crystallize in the cubic structure, however, evident changes in the preferred orientation were found when increasing the film thickness. Atomic force micrographs of a 334-nm-thick film indicate a very uniform surface morphology composed of a sub-micrometer sized taper-like structure. Optical measurements show high transparency for all films and reveal a systematic change in the band gap energy with the film thickness.