Influence of laser-ablation plume dynamics on the room-temperature epitaxial growth of CeO2 on silicon

High-quality epitaxial CeO2 thin films were obtained on Si(001) buffered wi th a yttria-stabilised zirconia layer by pulsed laser deposition. Although the best structural properties were achieved at high substrate temperature, high-quality epitaxy was obtained even at room temperature. Epitaxial grow th at low temperature is promoted by the high kinetic energy of particles r eaching the substrate. The oxygen pressure and target-substrate distance ha d a strong influence on the crystallographic structure and surface morpholo gy in low-temperature deposition. This behaviour is attributed to a change in the kinetic energy of the particles, which was evaluated from the plasma expansion velocity determined by an intensified CCD camera. If a shock wav e forms, a minimum substrate temperature of 550 degrees C is necessary for epitaxial growth.