Multiphase CuO z–CeO 2− δ thin films by pulsed laser deposition technique: experimental texture evolutions and kinetics modeling

Abstract

CeO 2 thin films for gas sensors doped with Cu were elaborated by pulsed-laser deposition (PLD) technique from Cu–CeO 2 targets. The films were deposited on oriented Si substrates for various deposition times. Scanning electron microscopy analyses evidenced correlations between crystalline texture of thin films, copper atom fractions and deposition times. A statistical study of grain sizes and texture allows evaluation of growth rates. From X-ray diffraction analyses, it was clearly established that texture effects are continuously modified as the Cu atom fraction increases: preferred (111) orientations of CeO 2 crystals change into (200) orientations. Such morphological effects might be involved by the presence of a CuO z phase, formed during the condensation process and peculiarly associated with the laser deposition technique. A texture parameter R corresponding to the volume ratio of oriented phases is defined. A first modeling of this texture parameter as a function of Cu composition x and deposition time t is proposed.