Process–structure–property relations of micron thick Gd2O3 films deposited by reactive electron-beam physical vapor deposition (EB-PVD)

Grave, Daniel A.; Hughes, Zachary; Robinson, Joshua A.; Medill, T.P.; Hollander, Matthew J.; Stump, Anna L.; LaBella, Michael; Weng, Xiaojun; Wolfe, Douglas E.

doi:10.1016/j.surfcoat.2011.12.031

Cited by 16 publications

(4 citation statements)

References 22 publications

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“…A material’s surface texture affects local surface area and surface energy and hence has tremendous effect on its utility . The effect of surface texture has inspired advances like superhydrophobic/superhydrophilic and self-cleaning materials. − High surface area also affects adsorption of small molecules and particles, hence, potential applications in catalysis and drug delivery. − Most methods that modify surface texture are additive, − subtractive, − or a combination of both. − Additive methods rely on introduction of chemi- or physisorbed adducts on the surface, whereas subtractive methods achieve this goal by selective partial removal of material to alter surface features. In addition, top-down, − bottom-up, , and interfacial methods − are also utilized to obtain characteristic surface patterns.…”

Section: Introductionmentioning

confidence: 99%

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

et al. 2018

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Droplets capture an environment-dictated equilibrium state of a liquid material. Equilibrium, however, often necessitates nanoscale interface organization, especially with formation of a passivating layer. Herein, we demonstrate that this kinetics-driven organization may predispose a material to autonomous thermal-oxidative composition inversion (TOCI) and texture reconfiguration under felicitous choice of trigger. We exploit inherent structural complexity, differential reactivity, and metastability of the ultrathin (∼0.7-3 nm) passivating oxide layer on eutectic gallium-indium (EGaIn, 75.5% Ga, 24.5% In w/w) core-shell particles to illustrate this approach to surface engineering. Two tiers of texture can be produced after ca. 15 min of heating, with the first evolution showing crumpling, while the second is a particulate growth above the first uniform texture. The formation of tier 1 texture occurs primarily because of diffusion-driven oxide buildup, which, as expected, increases stiffness of the oxide layer. The surface of this tier is rich in Ga, akin to the ambient formed passivating oxide. Tier 2 occurs at higher temperature because of thermally triggered fracture of the now thick and stiff oxide shell. This process leads to inversion in composition of the surface oxide due to higher In content on the tier 2 features. At higher temperatures (≥800 °C), significant changes in composition lead to solidification of the remaining material. Volume change upon oxidation and solidification leads to a hollow structure with a textured surface and faceted core. Controlled thermal treatment of liquid EGaIn therefore leads to tunable surface roughness, composition inversion, increased stiffness in the oxide shell, or a porous solid structure. We infer that this tunability is due to the structure of the passivating oxide layer that is driven by differences in reactivity of Ga and In and requisite enrichment of the less reactive component at the metal-oxide interface.

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Section: Introductionmentioning

confidence: 99%

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

et al. 2018

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“…In principle, two different growth schemes can be used for the oxide growth by MBE, or analogous deposition techniques. First is the thermal evaporation of the rare-earth metal with simultaneous addition of oxygen to form the oxide on the heated Si substrate, − which allows a relatively low source temperature for the metal evaporation. This scheme bears the risk of detrimental effects of the free oxygen, such as formation of a parasitic SiO 2 interface layer, the degradation of hot filaments in the growth chamber, and the risk of silicide formation by reaction of the rare earth metal vapor with the heated silicon .…”

Section: Introductionmentioning

confidence: 99%

Oxygen-Deficient Oxide Growth by Subliming the Oxide Source Material: The Cause of Silicide Formation in Rare Earth Oxides on Silicon

Bierwagen

Proessdorf

Niehle

et al. 2013

Crystal Growth & Design

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The fundamental issue of oxygen stoichiometry in oxide thin film growth by subliming the source oxide is investigated by varying the additionally supplied oxygen during molecular beam epitaxy of RE2O3 (RE = Gd, La, Lu) thin films on Si(111). Supplying additional oxygen throughout the entire growth was found to prevent the formation of rare earth silicides observed in films grown without an oxygen source. Postgrowth vacuum annealing of oxygen stoichiometric films did not lead to silicide formation thereby confirming that the silicides do not form as a result of an interface instability at growth temperature in vacuum but rather due to an oxygen deficiency in the source vapor. The average oxygen deficiency of the rare-earth containing species in the source vapor was quantified by the 18O tracer technique and correlated with that of the source material, which gradually decomposed during sublimation. Therefore, any oxide growth by sublimation of the oxide source material requires additional oxygen to realize oxygen stoichiometric films.

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“…As thin (epitaxial) layers grown on silicon, they represent, intrinsically or after doping, possible high-k (dielectric constant) gate dielectrics for modern metal-oxide-semiconductor devices [8]. They can also be buffers for growth of alternative semiconductors, the choice of which depends on the phase of the REO layer underneath [9]; regarding the REO phase, it has also been shown in GO that the monoclinic structure has a higher k value than its cubic counterpart [10]. In the case of these microelectronics applications, designing layers with control over composition, dopant concentration and crystallographic structure would be highly desirable for high-performance devices.…”

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confidence: 99%

Depth-dependent phase change in Gd2O3 epitaxial layers under ion irradiation

Mejai

Debelle

Thomé

et al. 2015

Applied Physics Letters

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Epitaxial Gd2O3 thin layers with the cubic structure were irradiated with 4-MeV Au 2+ ions in the 10 13-10 15 cm-2 fluence range. X-ray diffraction indicates that ion irradiation induces a cubic to monoclinic phase change. Strikingly, although the energy-deposition profile of the Au 2+ ions is constant over the layer thickness, this phase transformation is depth-dependent, as revealed by a combined X-ray diffraction and ion channeling analysis. In fact, the transition initiates very close to the surface and propagates inwards, which can be explained by an assisted migration process of irradiation-induced defects. This result is promising for developing a method to control the thickness of the rare-earth oxide crystalline phases.

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Process–structure–property relations of micron thick Gd2O3 films deposited by reactive electron-beam physical vapor deposition (EB-PVD)

Cited by 16 publications

References 22 publications

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

Autonomous Thermal-Oxidative Composition Inversion and Texture Tuning of Liquid Metal Surfaces

Oxygen-Deficient Oxide Growth by Subliming the Oxide Source Material: The Cause of Silicide Formation in Rare Earth Oxides on Silicon

Depth-dependent phase change in Gd2O3 epitaxial layers under ion irradiation

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