Selective Growth of Al2O3 on Size-Selected Platinum Clusters by Atomic Layer Deposition

In heterogeneous catalysis, atomic layer deposition (ALD) has been developed as a tool to stabilize and reduce carbon deposition on supported nanoparticles. Here, we discuss use of high vacuum ALD to deposit alumina films on size-selected, sub-nanometer Pt/SiO2 model catalysts. Mass-selected Pt24 clusters were deposited on oxidized Si(100), to form model Pt24/SiO2 catalysts with particles shown to be just under 1 nm, with multilayer three dimensional structure. Alternating exposures to trimethylaluminum and water vapor in an ultra-high vacuum chamber were used to grow alumina on the samples without exposing them to air. The samples were probed in situ using X-ray photoelectron spectroscopy (XPS), low-energy ion scattering spectroscopy (ISS), and CO temperature-programmed desorption (TPD). Additional samples were prepared for ex situ experiments using grazing incidence small angle x-ray scattering spectroscopy (GISAXS). Alumina growth is found to initiate at least 60 times more efficiently at the Pt24 cluster sites, compared to bare SiO2/Si, with a single ALD cycle depositing a full alumina layer on top of the clusters, with substantial additional alumina growth initiating on SiO2 sites surrounding the clusters. As a result, the clusters were completely passivated, with no exposed Pt binding sites.

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Oxygen Vacancies at the γ-Al2O3/STO Heterointerface Grown by Atomic Layer Deposition

MRS Proceedings ◽

10.1557/opl.2015.294 ◽

2015 ◽

Vol 1730 ◽

Author(s):

Thong Q. Ngo ◽

Martin D. McDaniel ◽

Agham Posadas ◽

Alexander A. Demkov ◽

John G. Ekerdt

Keyword(s):

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Oxygen Vacancies ◽

Atomic Layer ◽

High Energy ◽

Ex Situ ◽

X Ray ◽

Layer Deposition ◽

Dimensional Electron Gas

ABSTRACTWe report the epitaxial growth of γ-Al2O3 on SrTiO3 (STO) substrates by atomic layer deposition (ALD). The ALD growth of γ-Al2O3 on STO(001) single crystal substrates was performed at a temperature of 345 °C. Trimethylaluminum and water were used as co-reactants. In-situ reflection high-energy electron diffraction and ex-situ x-ray diffraction were used to determine the crystallinity of the Al2O3 films. In-situ x-ray photoelectron spectroscopy was used to characterize the Al2O3/STO heterointerface. The formation of a Ti3+ feature is observed in the Ti 2p spectrum of STO after the first few ALD cycles of Al2O3 and even after exposure of the STO substrate to trimethylaluminum alone at 345 °C. The presence of a Ti3+ feature is a direct indication of oxygen vacancies at the Al2O3/STO heterointerface, which provide the carriers for the quasi-two dimensional electron gas at the interface.

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Atomic Layer Deposition of SrO: Substrate and Temperature Effects

MRS Proceedings ◽

10.1557/opl.2012.1698 ◽

2012 ◽

Vol 1494 ◽

pp. 179-183

Author(s):

Han Wang ◽

Xiaoqiang Jiang ◽

Brian G. Willis

Keyword(s):

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Atomic Layer ◽

Ex Situ ◽

Hydroxyl Groups ◽

Initial Growth ◽

X Ray ◽

Steady Growth ◽

Layer Deposition

ABSTRACTThe atomic layer deposition (ALD) of SrO was conducted on various oxide surfaces by using strontium bis(tri-isopropylcyclopentadienyl) and water at deposition temperatures of 200 and 250°C. The initial and steady growth behaviors were studied by in-situ spectroscopic ellipsometry and ex-situ X-ray photoelectron spectroscopy. For initial growth, the growth per cycle (GPC) of SrO not only depends on the concentration of hydroxyl groups but also the formation of interfacial Sr-O-Si bonds. For the steady growth, in-situ annealing was used to enhance the growth rate and multiple growth regions were identified.

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Ex-situ X-ray diffraction analysis of electrode strain at TiO2 atomic layer deposition/α-MoO3 interface in a novel aqueous potassium ion battery

Journal of Power Sources ◽

10.1016/j.jpowsour.2016.03.064 ◽

2016 ◽

Vol 316 ◽

pp. 160-169 ◽

Cited By ~ 27

Author(s):

Nicholas David Schuppert ◽

Santanu Mukherjee ◽

Alex M. Bates ◽

Eun-Jin Son ◽

Moon Jong Choi ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Diffraction Analysis ◽

Atomic Layer ◽

Potassium Ion ◽

Ex Situ ◽

X Ray Diffraction ◽

X Ray ◽

Layer Deposition

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Air Annealing Effect on Oxygen Vacancy Defects in Al-doped ZnO Films Grown by High-Speed Atmospheric Atomic Layer Deposition

Molecules ◽

10.3390/molecules25215043 ◽

2020 ◽

Vol 25 (21) ◽

pp. 5043

Author(s):

Chia-Hsun Hsu ◽

Xin-Peng Geng ◽

Wan-Yu Wu ◽

Ming-Jie Zhao ◽

Xiao-Ying Zhang ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Band Gap ◽

Photoelectron Spectroscopy ◽

High Speed ◽

Oxygen Vacancies ◽

Annealing Temperature ◽

Atomic Layer ◽

Zno Films ◽

X Ray ◽

Layer Deposition

In this study, aluminum-doped zinc oxide (Al:ZnO) thin films were grown by high-speed atmospheric atomic layer deposition (AALD), and the effects of air annealing on film properties are investigated. The experimental results show that the thermal annealing can significantly reduce the amount of oxygen vacancies defects as evidenced by X-ray photoelectron spectroscopy spectra due to the in-diffusion of oxygen from air to the films. As shown by X-ray diffraction, the annealing repairs the crystalline structure and releases the stress. The absorption coefficient of the films increases with the annealing temperature due to the increased density. The annealing temperature reaching 600 °C leads to relatively significant changes in grain size and band gap. From the results of band gap and Hall-effect measurements, the annealing temperature lower than 600 °C reduces the oxygen vacancies defects acting as shallow donors, while it is suspected that the annealing temperature higher than 600 °C can further remove the oxygen defects introduced mid-gap states.

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Porous Silicon-Zinc Oxide Nanocomposites Prepared by Atomic Layer Deposition for Biophotonic Applications

Materials ◽

10.3390/ma13081987 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1987 ◽

Cited By ~ 3

Author(s):

Mykola Pavlenko ◽

Valerii Myndrul ◽

Gloria Gottardi ◽

Emerson Coy ◽

Mariusz Jancelewicz ◽

...

Keyword(s):

Zinc Oxide ◽

Optical Properties ◽

Porous Silicon ◽

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Atomic Layer ◽

Visible Range ◽

Optical Biosensing ◽

X Ray ◽

Layer Deposition

In the current research, a porous silicon/zinc oxide (PSi/ZnO) nanocomposite produced by a combination of metal-assisted chemical etching (MACE) and atomic layer deposition (ALD) methods is presented. The applicability of the composite for biophotonics (optical biosensing) was investigated. To characterize the structural and optical properties of the produced PSi/ZnO nanocomposites, several studies were performed: scanning and transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance, and photoluminescence (PL). It was found that the ALD ZnO layer fully covers the PSi, and it possesses a polycrystalline wurtzite structure. The effect of the number of ALD cycles and the type of Si doping on the optical properties of nanocomposites was determined. PL measurements showed a “shoulder-shape” emission in the visible range. The mechanisms of the observed PL were discussed. It was demonstrated that the improved PL performance of the PSi/ZnO nanocomposites could be used for implementation in optical biosensor applications. Furthermore, the produced PSi/ZnO nanocomposite was tested for optical/PL biosensing towards mycotoxins (Aflatoxin B1) detection, confirming the applicability of the nanocomposites.

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Atomic Layer Deposition of TiN below 600 K Using N2H4

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.282.232 ◽

2018 ◽

Vol 282 ◽

pp. 232-237

Author(s):

Adam Hinckley ◽

Anthony Muscat

Keyword(s):

Growth Rate ◽

Atomic Layer Deposition ◽

Titanium Nitride ◽

Photoelectron Spectroscopy ◽

Film Growth ◽

Detection Limits ◽

Atomic Layer ◽

Volatile Species ◽

X Ray ◽

Layer Deposition

Atomic layer deposition (ALD) was used to grow titanium nitride (TiN) on SiO2with TiCl4and N2H4. X-ray photoelectron spectroscopy (XPS) and ellipsometry were used to characterize film growth. A hydrogen-terminated Si (Si-H) surface was used as a reference to understand the reaction steps on SPM cleaned SiO2. The growth rate of TiN at 573 K doubled on Si-H compared to SiO2because of the formation of Si-N bonds. When the temperature was raised to 623 K, O transferred from Ti to Si to form Si-N when exposed to N2H4. Oxygen and Ti could be removed at 623 K by TiCl4producing volatile species. The added surface reactions reduce the Cl in the film below detection limits.

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Solar Absorber Cu2ZnSnS4 and its Parent Multilayers ZnS/SnS2/Cu2S Synthesized by Atomic Layer Deposition and Analyzed by X-ray Photoelectron Spectroscopy

Surface Science Spectra ◽

10.1116/1.4922822 ◽

2015 ◽

Vol 22 (1) ◽

pp. 81-99 ◽

Cited By ~ 2

Author(s):

Sergey V. Baryshev ◽

Shannon C. Riha ◽

Alexander V. Zinovev

Keyword(s):

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Atomic Layer ◽

X Ray ◽

Solar Absorber ◽

Layer Deposition

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Nickel Supported on Mesoporous Zirconium Oxide by Atomic Layer Deposition: Initial Fixed-Bed Reactor Study

10.26434/chemrxiv.7204847.v1 ◽

2018 ◽

Author(s):

Riikka Puurunen ◽

Pauline Voigt ◽

Eero Haimi ◽

Jouko Lahtinen ◽

You Wayne Cheah ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Photoelectron Spectroscopy ◽

Fixed Bed ◽

Atomic Layer ◽

Nickel Catalysts ◽

Fixed Bed Reactor ◽

Bet Surface Area ◽

X Ray ◽

Fluorescence Measurements ◽

Layer Deposition

Atomic layer deposition (ALD) is gaining attention as a catalyst preparation method able to produce metal (oxide, sulphide, etc.) nanoparticles of uniform size down to single atoms. This work reports our initial experiments to support nickel on mesoporous zirconia. Nickel (2,2,6,6-tetramethyl-3,5-heptanedionato)2 [Ni(thd)2] was reacted in a fixed-bed ALD reactor with zirconia, characterised with BET surface area of 72 m2/g and mean pore size of 14 nm. According to X-ray fluorescence measurements, the average nickel loading on the top part of the support bed was on the order of 1 wt-%, corresponding to circa one nickel atom per square nanometre. Cross-sectional scanning electron microscopy combined with energy-dispersive spectroscopy confirmed that in the top part of the fixed support bed, nickel was distributed throughout the zirconia particles. X-ray photoelectron spectroscopy indicated the nickel oxidation state to be two. Organic thd ligands remained complete on the surface after the Ni(thd)2 reaction with zirconia, as followed with diffuse reflectance infrared Fourier transform spectroscopy. The ligands could be fully removed by oxidation at 400 °C. These initial results indicate that nickel catalysts on zirconia can likely be made by ALD. Before catalytic testing, in addition to increasing the nickel loading by repeated ALD cycles, optimization of the process parameters is required to ensure uniform distribution of nickel throughout the support bed and within the zirconia particles.

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