Violet-blue luminescence from hafnium oxide layers doped with CeCl3 prepared by the spray pyrolysis process

HfO2:CeCl3 coatings were deposited by the spray pyrolysis method employing hafnium dichloride oxide and CeCl3 dissolved in deionized water (18 M Omega/cm). The room temperature photoluminescence characteristics of the HfO2:CeCl3 films were studied as a function of the deposition parameters such as doping concentrations and substrate temperature. The presence of two different Ce3+ centres in HfO2 is detected from photoluminescence measurements. A reduction of the luminescence intensity is observed with an increase of both the CeCl3 concentration and the deposition temperature. X-ray diffraction measurements of these films showed that the crystalline structure depends on the substrate temperature. For substrate temperatures less than 350 degrees C the deposited films are almost amorphous, while substrate temperatures higher than 400 degrees C produce diffraction peaks corresponding to the monoclinic phase of HfO2. The chemical composition of the films as determined by energy dispersive spectroscopy is also reported. Furthermore, the surface morphology characteristics of the coatings, as a function of the deposition temperature, are also presented. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.