SEARCH · Engineering Papers
Results for “EPITAXY”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Seeding Atomic Layer Deposition of High- k Dielectrics on Epitaxial Graphene with Organic Self-Assembled Monolayers
Explore the source record for details and available documents.
Reversible Redox Reactions in an Epitaxially Stabilized SrCoO{sub x} Oxygen Sponge
Abstract not provided
Searching for a route to synthesize in situ epitaxial Pr 2 Ir 2 O 7 thin films with thermodynamic methods
In situ growth of pyrochlore iridate thin films has been a long-standing challenge due to the low reactivity of Ir at low temperatures and the vaporization of volatile gas species such as IrO 3 (g) and IrO 2 (g) at high temperatures and high P O2 . To address this challenge, we combine thermodynamic analysis of the Pr-Ir-O 2 system with experimental results from the conventional physical vapor deposition (PVD) technique of co-sputtering. Our results indicate that only high growth temperatures yield films with crystallinity sufficient for utilizing and tailoring the desired topological electronic properties and the in situ synthesis of Pr 2 Ir 2 O 7 thin films is fettered by the inability to grow with P O2 on the order of 10 Torr at high temperatures, a limitation inherent to the PVD process. Thus, we suggest techniques capable of supplying high partial pressure of key species during deposition, in particular chemical vapor deposition (CVD), as a route to synthesis of Pr 2 Ir 2 O 7 .
Growth and characterization of epitaxially stabilized ceria(001) nanostructures on Ru(0001)
We have studied (001) surface terminated cerium oxide nanoparticles grown on a ruthenium substrate using physical vapor deposition. Their morphology, shape, crystal structure, and chemical state are determined by low-energy electron microscopy and micro-diffraction, scanning probe microscopy, and synchrotron-based X-ray absorption spectroscopy. Square islands are identified as CeO 2 nanocrystals exhibiting a (001) oriented top facet of varying size; they have a height of about 7 to 10 nm and a side length between about 50 and 500 nm, and are terminated with a p(2 × 2) surface reconstruction. Micro-illumination electron diffraction reveals the existence of a coincidence lattice at the interface to the ruthenium substrate. The orientation of the side facets of the rod-like particles is identified as (111); the square particles are most likely of cuboidal shape, exhibiting (100) oriented side facets. Lastly, the square and needle-like islands are predominantly found at step bunches and may be grown exclusively at temperatures exceeding 1000 °C.
Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material
Explore the source record for details and available documents.
Epitaxial growth of (1 1 1)-oriented spinel CoCr 2 O 4 /Al 2 O 3 heterostructures
High quality (1 1 1)-oriented CoCr 2 O 4 /Al 2 O 3 heterostructures were synthesized on the sapphire (0 0 0 1) single crystal substrates by pulsed laser deposition. The structural properties are demonstrated by in-situ reflection high energy electron diffraction, atomic force microscopy, X-ray reflectivity, and X-ray diffraction. X-ray photoemission spectroscopy confirms that the films possess the proper chemical stoichiometry. In conclusion, this work offers a pathway to fabricating spinel type artificial quasi-two-dimensional frustrated lattices by means of geometrical engineering.
Brownmillerite Phase Formation and Evolution in Epitaxial Strontium Ferrite Heterostructures
By controlling the synthesis and process conditions, we show that the oxygen vacancy channels (OVCs) of Brownmillerite-structured SrFeO2.5+? (0=??0.5) thin films can be oriented differently on the same LaAlO3(001) substrate due to either a bottom up or top down synthesis route. The brownmillerite structure formation and evolution processes yield distinctively different optical and electronic properties, owing to the difference in the oxygen content and OVC configuration in the resultant films. Moreover, we also show that in situ transmission electron microscopy (TEM) can induce oxygen loss and drive a phase transition from perovskite SrFeO3 to brownmillerite SrFeO2.5+? with mixed horizontally and vertically aligned OVCs. The dimensionality change during the TEM sample preparation makes the bottom up and top down model not applicable. Our results offer further insight into the phase stability and oxygen-diffusion mechanisms, which is important for the predictive synthesis of novel functional materials.
Geometry of epitaxial GaAs/(Al,Ga)As quantum dots as seen by excitonic spectroscopy
Not Available
Local atomic and electronic structures of epitaxial strained LaCoO 3 thin films
Not Available
Strain-tunable extraordinary magnetocrystalline anisotropy in Sr 2 CrReO 6 epitaxial films
Not Available
Stability of the M2 phase of vanadium dioxide induced by coherent epitaxial strain
Not Available
Large Isosymmetric Reorientation of Oxygen Octahedra Rotation Axes in Epitaxially Strained Perovskites
Not Available
Chemically Resolved Interface Structure of Epitaxial Graphene on SiC(0001)
Abstract not provided