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Nucleation, morphology, and structure of sub‐nm thin ceria islands on Rh(111)
Author(s) -
Flege Jan Ingo,
Höcker Jan,
Sadowski Jerzy T.,
Senanayake Sanjaya D.,
Falta Jens
Publication year - 2019
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6567
Subject(s) - nucleation , photoemission electron microscopy , substrate (aquarium) , materials science , low energy electron microscopy , layer (electronics) , morphology (biology) , crystallography , rhodium , island growth , electron microscope , low energy electron diffraction , oxide , epitaxy , nanotechnology , electron diffraction , chemistry , diffraction , catalysis , metallurgy , optics , geology , paleontology , biochemistry , physics , oceanography , organic chemistry
The early stages of ceria growth on Rh(111) at high temperature have been investigated by low‐energy electron microscopy and photoemission electron microscopy. Ceria was deposited by reactive Ce deposition at substrate temperatures between 700°C and 900°C in an oxygen ambient of 5 × 10 −7 Torr. At 700°C, we observe a high nucleation density of 100‐nm‐sized islands. With elevated temperature, the average island size increases, and the nucleation density decreases. Triangularly shaped islands nucleate preferentially at step edges, with seemingly abrupt interfaces between Ce and Rh. At 900°C, the island edges are still straight, but during growth the islands lose their triangular form. Instead, growth along the substrate step edges becomes favorable, leading to a maze‐like morphology. Atomic force microscopy reveals islands of 0.3 to 0.6‐nm height, consistent with ceria islands formed by one or two trilayers (O―Ce―O) of ceria. Moreover, the second layer of the islands is also triangularly shaped, with lateral dimensions of 50 nm and similar step heights. IV‐LEEM analysis leads to the conclusion that the rhodium surface is covered by a layer of reduced cerium oxide, which is partially overgrown by smaller islands of CeO 2 .