2 research outputs found
Optical Properties of Vanadium Pentoxide Deposited by ALD
Nanostructures of V<sub>2</sub>O<sub>5</sub> find important
technological
applications in optics, catalysis, and lithium ion batteries. Their
optical properties and surface roughness are important parameters
in these respects. Here we report on atomic layer deposition (ALD)
of V<sub>2</sub>O<sub>5</sub> using the β-diketonate VO(thd)<sub>2</sub> and ozone as precursors. In this work, X-ray diffraction,
AFM, ellipsometry, and UV–vis-spectroscopy are used to show
that the crystallographic orientation, optical properties, band gap,
and surface roughness of the derived films are correlated and can
be varied by controlling deposition temperature and film thickness.
The band gap of the samples varies between 2.70 and 2.35 eV. The observed
growth rate varies between 0.1 to 1 Å/cycle depending on deposition
temperature and the number of cycles. This large variation in growth
rate provides an interesting case of ALD growth, which can be rationalized
in terms of a geometric crystal growth model
Atomic Layer Deposition of Spinel Lithium Manganese Oxide by Film-Body-Controlled Lithium Incorporation for Thin-Film Lithium-Ion Batteries
Lithium
manganese oxide spinels are promising candidate materials
for thin-film lithium-ion batteries owing to their high voltage, high
specific capacity for storage of electrochemical energy, and minimal
structural changes during battery operation. Atomic layer deposition
(ALD) offers many benefits for preparing all-solid-state thin-film
batteries, including excellent conformity and thickness control of
the films. Yet, the number of available lithium-containing electrode
materials obtained by ALD is limited. In this article, we demonstrate
the ALD of lithium manganese oxide, Li<sub><i>x</i></sub>Mn<sub>2</sub>O<sub>4</sub>, from Mn(thd)<sub>3</sub>, Li(thd), and
ozone. Films were polycrystalline in their as-deposited state and
contained less than 0.5 at. % impurities. The chemical reactions between
the lithium precursor and the film were found not to be purely surface-limited
but to include a bulk component as well, contrary to what is usually
found for ALD processes. In addition, we show a process for using
Li(thd)/ozone and LiO<sup><i>t</i></sup>Bu/water treatments
to transform ALD-MnO<sub>2</sub> and ALD-V<sub>2</sub>O<sub>5</sub> into Li<sub><i>x</i></sub>Mn<sub>2</sub>O<sub>4</sub> and
Li<sub><i>x</i></sub>V<sub>2</sub>O<sub>5</sub>, respectively.
The formed Li<sub><i>x</i></sub>Mn<sub>2</sub>O<sub>4</sub> films were characterized electrochemically and found to show high
electrochemical capacities and high cycling stabilities