Factors controlling the microstructure of Ce0.9Gd0.1O2-δ films in pulsed laser deposition process

Films of Ce0.9Gd0.1O2-delta (CGO10) are prepared at a range of conditions by pulsed laser deposition (PLD) on a single crystal Si (100) and MgO (100), and on a polycrystalline Pt/MgO (100) substrate. The relationship between the film microstructure, crystallography, chemical composition and PLD processing parameters is studied. It is found that the laser fluence has no significant impact on the film density, whereas the substrate temperature and the oxygen pressure are of essential importance for the film microstructure development. The reduction of deposition temperature, down to 250 oC, together with a lowered oxygen pressure of 0.05 mbar, significantly inhibits the growth of columnar structures. Further decrease in oxygen pressure, to 0.005 mbar, promotes films densification, but a stress build-up is observed and leads to a lattice-parameter enlargement of the coatings. The chemical films composition is affected by the applied fluence. At a low fluence, 0.5 J/cm², a congruent transfer is obtained while a relative Gd enrichment results for substantially higher (3.5-5.5 J/cm²).