Surface morphology of ultrathin hex-Pr<sub>2</sub>O<sub>3</sub>films on Si(1 1 1)

Wilkens, H.; Rodewald, Jari; Gevers, S.; Zoellner, M. H.; Schroeder, Thomas; Wollschläger, J.

doi:10.1088/0022-3727/46/28/285306

Cited by 7 publications

(5 citation statements)

References 25 publications

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“…Our studies reveal that amorphous germanium is a feasible capping layer since it can be removed by annealing in a diluted oxygen atmosphere without changing the structure of the underlying hex-Pr 2 O 3 (0001) film as shown by combined AES and GIXRD measurements. 123 Furthermore, high resolution SPA-LEED measurements of the hex-Pr 2 O 3 (0001) surface exhibit a hexagonal (1 Â 1) diffraction pattern with obviously no intensity variations of the first order diffraction spots as seen in Fig. 12(a) while a threefold symmetry is observed for (111) surfaces of films with a bulk cubic structure as (seen in Fig.…”

Section: Iii2 Surface Structure and Morphologymentioning

confidence: 91%

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Controlling the physics and chemistry of binary and ternary praseodymium and cerium oxide systems

Niu

Zoellner

Schroeder

et al. 2015

Phys. Chem. Chem. Phys.

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Rare earth praseodymium and cerium oxides have attracted intense research interest in the last few decades, due to their intriguing chemical and physical characteristics. An understanding of the correlation between structure and properties, in particular the surface chemistry, is urgently required for their application in microelectronics, catalysis, optics and other fields. Such an understanding is, however, hampered by the complexity of rare earth oxide materials and experimental methods for their characterisation. Here, we report recent progress in studying high-quality, single crystalline, praseodymium and cerium oxide films as well as ternary alloys grown on Si(111) substrates. Using these well-defined systems and based on a systematic multi-technique surface science approach, the corresponding physical and chemical properties, such as the surface structure, the surface morphology, the bulk-surface interaction and the oxygen storage/release capability, are explored in detail. We show that specifically the crystalline structure and the oxygen stoichiometry of the oxide thin films can be well controlled by the film preparation method. This work leads to a comprehensive understanding of the properties of rare earth oxides and highlights the applications of these versatile materials. Furthermore, methanol adsorption studies are performed on binary and ternary rare earth oxide thin films, demonstrating the feasibility of employing such systems for model catalytic studies. Specifically for ceria systems, we find considerable stability against normal environmental conditions so that they can be considered as a "materials bridge" between surface science models and real catalysts.

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Section: Iii2 Surface Structure and Morphologymentioning

confidence: 91%

“…From the analysis of the oscillating function, the surface morphology of the hex-Pr 2 O 3 (0001) film is deduced. 123 The surface consists of small grains (B1.7 nm) but is very smooth since only few grains exhibit single atomic steps of full unit cell height as indicated in the model presented in Fig. 15.…”

Section: Iii2 Surface Structure and Morphologymentioning

confidence: 99%

Controlling the physics and chemistry of binary and ternary praseodymium and cerium oxide systems

Niu

Zoellner

Schroeder

et al. 2015

Phys. Chem. Chem. Phys.

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“…[32][33][34] The surfaces exhibit mosaics with terraces which are separated by monoatomic steps. However, the Ce/Pr ratio has a strong impact on the structure and morphology of the surfaces.…”

Section: Discussionmentioning

confidence: 99%

“…The spot profile analysis shows similarities to pure cerium and praseodymium oxide films grown on Si(111). [32][33][34] The surfaces exhibit mosaics with terraces which are separated by monoatomic steps. However, the Ce/Pr ratio has a strong impact on the structure and morphology of the surfaces.…”

Section: Discussionmentioning

confidence: 99%

“…We assume that the hex -cub transformation mentioned above is responsible for this effect since a similar increase of the mosaic spread can be observed for this transition in pure praseodymia films. [32][33][34] With increasing PDA temperature the mosaic spread becomes larger for the samples with low and moderate praseodymium concentration while it decreases for the sample with high praseodymium concentration. All samples approach a final value of E0.91 for the mosaic spread.…”

Section: B Spot Profile Analysismentioning

confidence: 99%

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Post deposition annealing of epitaxial Ce_1−xPr_xO_2−δfilms grown on Si(111)

Wilkens

Spieß

Zoellner

et al. 2015

Phys. Chem. Chem. Phys.

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In this work the structural and morphological changes of Ce 1Àx Pr x O 2Àd (x = 0.20, 0.35 and 0.75) films grown on Si(111) due to post deposition annealing are investigated by low energy electron diffraction combined with a spot profile analysis. The surface of the oxide films exhibit mosaics with large terraces separated by monoatomic steps. It is shown that the Ce/Pr ratio and post deposition annealing temperature can be used to tune the mosaic spread, terrace size and step height of the grains. The morphological changes are accompanied by a phase transition from a fluorite type lattice to a bixbyite structure. Furthermore, at high PDA temperatures a silicate formation via a polycrystalline intermediate state is observed.

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