First principles study of reactions in alucone growth: the role of the organic precursor

Muriqi, Arbresha; Nolan, Michael

doi:10.1039/d0dt01376e

Cited by 9 publications

(9 citation statements)

References 61 publications

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“…However, despite the reduction of OH groups on the surface, terminal oxygen sites of the flat EG can also serve as active sites and they can bind with other TiCl4 molecules in the following cycle, similar to TMA-EG alucones. [38] The GL molecule is a triol with three OH active groups, so even in the case of double reactions for GL the third OH group is available for further reactions.…”

Section: Resultsmentioning

confidence: 99%

“…[24][38] [39][40] DFT studies show that the aliphatic diol precursors, namely EG and GL, when combined with TMA, undergo double reactions, binding with the surface fragments through the two terminal -OH groups, and this phenomenon reduces the number of active sites and terminates the surface growth. [38] However, DFT results also show that this scheme depends on the metal precursor and the surface as the same aliphatic precursors behave differently when combined with Mg(Cp)2; EG still prefers to orient in a flat configuration and react twice with the surface, while GL prefers to lie in an upright configuration. This yields thicker GL-based magnesicone films, consistent with the experimental observations.…”

Section: Introductionmentioning

confidence: 99%

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Role of Titanium and Organic Precursors in Molecular Layer Deposition of “Titanicone” Hybrid Materials

Muriqi

Nolan

2022

Preprint

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The development of hybrid inorganic-organic films with well-controlled properties is important for many applications. Molecular layer deposition (MLD) allows the deposition of these hybrid films using sequential, self-limiting reactions, similar to atomic layer deposition (ALD). In this paper, we use first principles density functional theory (DFT) to investigate the growth mechanism of titanium-containing hybrid organic-inorganic MLD films, known as “titanicones”. We investigate in detail the chemistry between the most common Ti precursors, namely titanium tetrachloride (TiCl4) and tetrakis(dimethylamido)titanium (Ti(DMA)4,) and ethylene glycol (EG) and glycerol (GL) as the organic precursors. We analyse the impact of the substrate on the initial MLD reactions in titanicone film growth using three different surface models: anatase TiO2, rutile TiO2 and Al2O3. Calculated energetics show that while TiCl4 is reactive towards the anatase and rutile TiO2 surfaces, it is not reactive towards the Al2O3 surface. Ti(DMA)4 is reactive towards all surfaces. This is attributed to the stronger Ti-Cl bonds in TiCl4 compared to Ti-N bonds in Ti(DMA)4. Ti(DMA)4 also shows high reactivity to the organics compared to TiCl4. Double reactions of EG and GL with the TiCl3 species from TiCl4 and TiDMA species from Ti(DMA)4 are also explored to better understand the origin of the different thicknesses of EG-titanicone and GL-titanicone films observed in experimental work. We find that EG and GL coupled with TiCl4 can orient in a flat lying configuration on anatase while on rutile, the preferred orientation is upright. When combined with Ti(DMA)4, EG and GL prefer the flat lying configuration on all surfaces. This work shows that the choice of the surface and the metallic precursor has a major impact on the behaviour of organic species. DFT findings provide motivation to develop a low temperature rutile TiO2/titanicone film suggesting that the desired film growth could be achieved.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of Titanium and Organic Precursors in Molecular Layer Deposition of “Titanicone” Hybrid Materials

Muriqi

Nolan

2022

Preprint

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“…For diols this eliminates the active hydroxyls needed for growth, while for glycerol this is yielding a lower growth per cycle. 10 On the other hand, recent work using rigid aromatic backbones alleviates this problem, since, as demonstrated in recent DFT studies, 11 aromatic species prefer to interact in an upright mode rather than undergoing ‘double reactions’ and this results in higher growth rates.…”

Section: Introductionmentioning

confidence: 99%

Atomic/molecular layer deposition of cerium(iii) hybrid thin films using rigid organic precursors

et al. 2022

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“…Many studies show that the desired properties and the target thickness of a metalcone MLD film are not actually achieved. To help understand this, first principles density functional theory (DFT) calculations have been employed to explore the reaction mechanisms, energetics and the role of the organic precursors on the growth of hybrid films [24,[39][40][41]. DFT studies show that the aliphatic diol precursors, namely EG and GL, when combined with TMA, undergo double reactions, binding with the surface fragments through the two terminal OH groups, and this phenomenon reduces the number of active sites and terminates the surface growth [39].…”

Section: Introductionmentioning

confidence: 99%

Role of titanium and organic precursors in molecular layer deposition of “titanicone” hybrid materials

Muriqi¹,

Nolan²

2022

Beilstein J. Nanotechnol.

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The development of hybrid inorganic–organic films with well-controlled properties is important for many applications. Molecular layer deposition (MLD) allows the deposition of these hybrid films using sequential, self-limiting reactions, similar to atomic layer deposition (ALD). In this paper, we use first principles density functional theory (DFT) to investigate the growth mechanism of titanium-containing hybrid organic–inorganic MLD films, known as “titanicones”. We investigate in detail the chemistry between the most common Ti precursors, namely titanium tetrachloride (TiCl4) and tetrakis(dimethylamido)titanium (Ti(DMA)4), and ethylene glycol (EG) and glycerol (GL) as the organic precursors. We analyse the impact of the substrate on the initial MLD reactions in titanicone film growth using three different surface models: anatase TiO2, rutile TiO2 and Al2O3. Calculated energetics show that while TiCl4 is reactive towards the anatase and rutile TiO2 surfaces, it is not reactive towards the Al2O3 surface. Ti(DMA)4 is reactive towards all surfaces. This is attributed to the stronger Ti–Cl bonds in TiCl4 compared to Ti–N bonds in Ti(DMA)4. Ti(DMA)4 also shows high reactivity to the organics compared to TiCl4. Double reactions of EG and GL with the TiCl3 species from TiCl4 and TiDMA species from Ti(DMA)4 are also explored to better understand the origin of the different thicknesses of EG–titanicone and GL–titanicone films observed in experimental work. We find that EG and GL coupled with TiCl4 can orient in a flat lying configuration on anatase while on rutile, the preferred orientation is upright. When combined with Ti(DMA)4, EG and GL prefer the flat lying configuration on all surfaces. This work shows that the choice of the surface and the metallic precursor has a major impact on the behaviour of organic species. DFT findings provide motivation to develop a low temperature rutile TiO2/titanicone film suggesting that the desired film growth could be achieved.

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First principles study of reactions in alucone growth: the role of the organic precursor

Abstract: First principles investigation of the molecular mechanism of the growth of hybrid organic–inorganic thin films of aluminium alkoxides, known as “alucones”.

Cited by 9 publications

References 61 publications

Role of Titanium and Organic Precursors in Molecular Layer Deposition of “Titanicone” Hybrid Materials

Role of Titanium and Organic Precursors in Molecular Layer Deposition of “Titanicone” Hybrid Materials

Atomic/molecular layer deposition of cerium(iii) hybrid thin films using rigid organic precursors

Role of titanium and organic precursors in molecular layer deposition of “titanicone” hybrid materials

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