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Download fileChemical and Structural Configuration of Pt-Doped Metal Oxide Thin Films Prepared by Atomic Layer Deposition
journal contribution
posted on 2019-11-22, 18:33 authored by Ranjith K. Ramachandran, Matthias Filez, Eduardo Solano, Hilde Poelman, Matthias M. Minjauw, Michiel Van Daele, Ji-Yu Feng, Andrea La Porta, Thomas Altantzis, Emiliano Fonda, Alessandro Coati, Yves Garreau, Sara Bals, Guy B. Marin, Christophe Detavernier, Jolien DendoovenPt-doped semiconducting metal oxides and Pt metal clusters
embedded
in an oxide matrix are of interest for applications such as catalysis
and gas sensing, energy storage, and memory devices. Accurate tuning
of the dopant level is crucial for adjusting the properties of these
materials. Here, a novel atomic layer deposition (ALD)-based method
for doping Pt into In2O3 specifically, and metals
in metal oxides in general, is demonstrated. This approach combines
alternating exposures of Pt and In2O3 ALD processes
in a single “supercycle” followed by supercycle repetition
leading to multilayered nanocomposites. The atomic-level control of
ALD and its conformal nature make the method suitable for accurate
dopant control even on high-surface-area supports. The oxidation state,
local structural environment, and crystalline phase of the embedded
Pt dopants were obtained by means of X-ray characterization methods
and high-angle annular dark-field scanning transmission electron microscopy.
In addition, this approach allows characterization of the nucleation
stages of metal ALD processes by stacking those states multiple times
in an oxide matrix. Regardless of experimental conditions, a few Pt
ALD cycles lead to the formation of oxidized Pt species due to their
highly dispersed nature, as proven by X-ray absorption spectroscopy.
Grazing-incidence small-angle X-ray scattering and high-resolution
scanning transmission electron microscopy, combined with energy-dispersive
X-ray spectroscopy, show that Pt is evenly distributed in the In2O3 matrix without the formation of clusters. For
a larger number of Pt ALD cycles, typically >10, the oxidation
state
gradually evolves toward fully metallic, and metallic Pt clusters
are obtained within the In2O3 matrix. This
work reveals how tuning of the ALD supercycle approach for Pt doping
allows controlled engineering of the Pt compositional and structural
configurations within a metal oxide matrix.
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Keywords
energy-dispersive X-ray spectroscopyPt-Doped Metal OxideX-ray characterization methodsmetal ALD processesPt ALD cycles2 O 3 ALD processesAtomic Layer Deposition Pt-doped semiconducting metal oxides2 O 3 matrixhigh-angle annular dark-field scanning transmission electron microscopyX-ray absorption spectroscopyoxide matrix2 O 3scanning transmission electron microscopymetal oxide matrixPt metal clustersALD supercycle approachoxidation stateGrazing-incidence small-angle X-ray