PLD-grown Y2O3 thin films from Y metal: An advantageous alternative to films deposited from yttria

The pulsed laser deposition (PLD) of Y2O3 from a pure yttrium ablation targ et is performed for the first time and is shown to replace advantageously P LD from yttria targets. The films were grown on optical-quality MgO(100) an d sapphire(0001) substrates, the former yielding films with poorer crystall ine quality because of the large lattice misfit between film and substrate. Regardless of the growth conditions employed, films deposited from the ytt rium target consistently exhibit lower w-rocking curve values than films de posited from the oxide target, thus suggesting a lower degree of tilting be tween the growth planes of the film. Because of the higher absorption coeff icient of the metal target, the metal-deposited films exhibit a smoother fi lm surface than films deposited from the oxide target, which present locali zed surface outgrowths. The AFM study confirms that the roughness of the fi lms is smaller for Y- than for Y2O3-deposited films, but in both cases, it is strongly dependent on the total background gas pressure and on the chemi cal etching of the substrate surface prior to deposition. Cross-section spe cimens studied by transmission electron microscopy (TEM) showed that the re gion near the substrate-film interface is very smooth and that the inplane orientation of the films changes as a function of film thickness. XPS analy sis showed no obvious difference in bonding at the surface of the films dep osited from the different targets, indicating that the same level of oxidat ion occurred during the growth process of the film by each target.