Nanolaminates with Novel Properties Fabricated Using Atomic Layer Deposition Techniques

George, Steven M.

doi:10.21236/ada451599

Cited by 2 publications

(3 citation statements)

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“…As seen from TGA and DRIFTS data, the loss of excess hydroxyl groups and interstitial physisorbed water occurs at temperatures below 200 °C, with further dehydroxylation and, for films deposited at lower temperatures, additional water loss around 500 °C. The higher-temperature transition appears to be concurrent with pore formation in the overcoat, as shown by SAXS works elsewhere, ,, but the precise nature of this transition is still not clear. In the aforementioned references, which clearly demonstrate the onset of pore formation in TiO 2 and Al 2 O 3 films at 500 °C, the crystallization temperature of TiO 2 films was found to be the same as the temperature of pore formation. , The crystallization temperature of Al 2 O 3 was placed between 300 and 800 °C but otherwise not conclusively determined by the authors.…”

Section: Resultsmentioning

confidence: 83%

“…No further loss of mass in the AlO X film occurs upon heating to the film crystallization temperature, indicating that crystallization is distinct from hydroxyl and water loss. Considering that pores form rapidly well below 700 °C, , the temperature required for bulk crystallization of the overcoat, it is clear that reorganization of the Al 3+ cations to bulk γ- and δ-Al 2 O 3 is not the mechanism of pore formation. It is likely that loss of structural water and hydroxyl groups is responsible for the process of pore formation by the loss of hydrogen bonding between adjacent layers, accompanied by densification of the film due to cross-linking between disordered layers, without significant movement of Al 3+ in the oxygen lattice to form large crystalline transition alumina domains.…”

Section: Resultsmentioning

confidence: 99%

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Understanding Pore Formation in ALD Alumina Overcoats

George

Littlewood

Stair

2020

ACS Appl. Mater. Interfaces

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AlO X thin films deposited by atomic layer deposition (ALD) have previously been used to increase both stability and selectivity of supported palladium catalysts and are known to develop nanoscale porosity upon heating. Understanding the factors that affect ALD thin-film porosity enables future design of layered catalytic structures with tunable nanoscale features on industrially-relevant high-surface-area materials. In this study, porous and nonporous aluminum oxide supports with and without palladium nanoparticles were overcoated with thin films of 2–7 nm AlO X by ALD deposited at temperatures of 100, 200, and 300 °C. Hydroxyl loss and changes in surface chemistry were observed upon heating the films, and changes in surface area and pore volume of the annealed films were correlated to AlO X deposition temperature and the presence of Pd. Crystallization of the overcoat to γ-Al2O3 is shown to occur separately from hydroxyl loss and pore formation. A mechanistic understanding of pore formation in AlO X ALD films is obtained by reference to studies of the structural transformations accompanying the formation of transition aluminas from hydroxide precursors. Additionally, a direct and tunable correlation is established between pore development and the overall hydroxyl content of AlO X ALD coatings.

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Understanding Pore Formation in ALD Alumina Overcoats

George

Littlewood

Stair

2020

ACS Appl. Mater. Interfaces

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“…Or is the C-O-M bonding even possible? A detailed understanding would give a better insight for instance into the modification of DNA molecules by ALD and also into the growth of organic and inorganic nanolaminates that have been shown to be possible to deposit by ALD [14,15].…”

Section: Starting Surfacementioning

confidence: 99%

ALD Technology - Present and Future Challenges

Haukka

2007

ECS Trans.

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Atomic layer deposition (ALD) is one of the established techniques among the other chemical and physical deposition techniques of today. There is still, however, a number of challenges for ALD to meet regarding both manufacturing and growth chemistry. The main manufacturing obstacle is the throughput which inherently is low for ALD. In the chemistry side the precursor development plays a very important role together with the understanding of which ALD technique, thermal or plasma enhanced (PE), or even combined (PE)ALD/CVD to use for which application. In the future there will be an increasing need for the development of new ALD materials and for the detailed understanding of the growth of thin films and nanostructures not only on inorganic but also on organic surfaces.

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Nanolaminates with Novel Properties Fabricated Using Atomic Layer Deposition Techniques

Cited by 2 publications

References 1 publication

Understanding Pore Formation in ALD Alumina Overcoats

Understanding Pore Formation in ALD Alumina Overcoats

ALD Technology - Present and Future Challenges

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