How r-Plane Al2O3 Surface Modifications Impact the Growth of Epitaxial (001) CeO2 Thin Films

Abstract

We present evidence that it is the presence or absence of atomic terraces with a specific crystallographic orientation on the (102) Al 2 O 3 surface that promotes growth of single-crystal (001) CeO 2 films over polycrystalline (111) CeO 2 films. The CeO 2 film nucleates so that the [010] and [100] directions of the film align parallel and perpendicular to the terrace edges. In the absence of terraces, multidomain (111) CeO 2 films result in which the in-plane orientation of the two domains are rotated by 85.71°, so that a [110] CeO 2 direction aligns parallel to either the " 221 Â Ã or " 2 " 41 Â Ã Al 2 O 3 direction.

Measurement of radiation-enhanced diffusion of La in single crystal thin film CeO2

“…The rocking curve scan of the reference film is characterized by a narrow component (r $ 0.02°) and a broad component (r $ 0.4°), consistent with a portion of the film commensurate or in registry with the sapphire substrate and a portion of the film not in registry, respectively. Similar rocking curves have been observed from epitaxial (0 0 1) CeO 2 on r-plane sapphire and interpreted as nucleation along step edges (narrow mosaic) versus nucleation away from step edges (broad mosaic) [8]. We note the presence of a $0.1°offset between the narrow and the broad components in the rocking curves.…”

“…2 demonstrates that the as-grown un-irradiated film consisted of a singledomain. The fourfold symmetry observed from the (2 2 0) in-plane reflection is that expected of single crystal CeO 2 on r-plane sapphire, as observed by others [8,9]. Here it is important to draw a distinction between a highly textured polycrystalline film and a true single crystal film.…”

Three-dimensional graphoepitaxial growth of oxide films by pulsed laser deposition

“…It is known that the change of the orientation of the surface features can influence orientation of the growing films (see, e.g., [32][33][34]). Experiments in semiconductor heterostructures showed a broad variety of effects of changing the tilt axis direction in the habit plane.…”

Investigation into the impact of grain boundaries, film interface, and crystallographic orientation on the ionic conductivity of thin film gadolinium-doped ceria

“…The GDC sputtering target had a composition of (10%)Gd 2 O 3 (90%)CeO 2 . The growth process, which results in single crystal GDC films, has been reported in previous publications [9,18].…”

“…One oxygen vacancy is created for every two Trivalent Gadolinium atoms that replace quad-valent cerium atoms in the crystal structure according to Equation 1.0.4. [18].…”