The Early Steps of Molecule-to-Material Conversion in Chemical Vapor Deposition (CVD): A Case Study

Transition metal complexes with β-diketonate and diamine ligands are valuable precursors for the chemical vapor deposition (CVD) of metal oxide nanomaterials, but the metal-ligand bond cleavage mechanism on the growth surface is not clarified yet. We address this question by Density Functional Theory (DFT) and ab initio molecular dynamics (AIMD) in combination with the Bluemoon (BM) statistical sampling approach. AIMD simulations of the Zn β-diketonate-diamine complex Zn(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N’,N’-tetramethylethylenediamine) show that rolling diffusion of this precursor at 500 K on a hydroxylated silica slab leads to an octahedral-to-square pyramidal rearrangement of its molecular geometry. The free energy profile of the octahedral-to-square pyramidal conversion indicates that the process barrier (5.8 kcal/mol) is of the order of the thermal energy at the operating temperature. The formation of hydrogen bonds with surface hydroxyls plays a key role in aiding the cleavage of a Zn-O bond. In the square-pyramidal complex, the Zn center has a free coordination position, which might promote the interaction with incoming reagents on the deposition surface. These results provide a valuable atomistic insight on the molecule-to-material conversion process which, in perspective, might help to tailor by design the first nucleation stages of the target ZnO-based nanostructures.

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The Early Steps of Molecule-to-Material Conversion in Chemical Vapor Deposition (CVD): A Case Study

10.26434/chemrxiv.14125961 ◽

2021 ◽

Author(s):

Davide Barreca ◽

Ettore Fois ◽

Alberto Gasparotto ◽

Chiara Maccato ◽

Mario Oriani ◽

...

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Density Functional ◽

Bond Cleavage ◽

Chemical Vapor ◽

Molecular Geometry ◽

Growth Surface ◽

Surface Hydroxyls ◽

Metal Oxide Nanomaterials ◽

Diamine Ligands

Transition metal complexes with β-diketonate and diamine ligands are valuable precursors for the chemical vapor deposition (CVD) of metal oxide nanomaterials, but the metal-ligand bond cleavage mechanism on the growth surface is not clarified yet. We address this question by Density Functional Theory (DFT) and ab initio molecular dynamics (AIMD) in combination with the Bluemoon (BM) statistical sampling approach. AIMD simulations of the Zn β-diketonate-diamine complex Zn(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N’,N’-tetramethylethylenediamine) show that rolling diffusion of this precursor at 500 K on a hydroxylated silica slab leads to an octahedral-to-square pyramidal rearrangement of its molecular geometry. The free energy profile of the octahedral-to-square pyramidal conversion indicates that the process barrier (5.8 kcal/mol) is of the order of the thermal energy at the operating temperature. The formation of hydrogen bonds with surface hydroxyls plays a key role in aiding the cleavage of a Zn-O bond. In the square-pyramidal complex, the Zn center has a free coordination position, which might promote the interaction with incoming reagents on the deposition surface. These results provide a valuable atomistic insight on the molecule-to-material conversion process which, in perspective, might help to tailor by design the first nucleation stages of the target ZnO-based nanostructures.

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The Early Steps of Molecule-to-Material Conversion in Chemical Vapor Deposition (CVD): A Case Study

Molecules ◽

10.3390/molecules26071988 ◽

2021 ◽

Vol 26 (7) ◽

pp. 1988

Author(s):

Davide Barreca ◽

Ettore Fois ◽

Alberto Gasparotto ◽

Chiara Maccato ◽

Mario Oriani ◽

...

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Density Functional ◽

Chemical Vapor ◽

Molecular Geometry ◽

Ab Initio Molecular Dynamics ◽

Growth Surface ◽

Hydroxyl Groups ◽

Surface Hydroxyl ◽

Order Of Magnitude

Transition metal complexes with β-diketonate and diamine ligands are valuable precursors for chemical vapor deposition (CVD) of metal oxide nanomaterials, but the metal-ligand bond dissociation mechanism on the growth surface is not yet clarified in detail. We address this question by density functional theory (DFT) and ab initio molecular dynamics (AIMD) in combination with the Blue Moon (BM) statistical sampling approach. AIMD simulations of the Zn β-diketonate-diamine complex Zn(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N′,N′-tetramethylethylenediamine), an amenable precursor for the CVD of ZnO nanosystems, show that rolling diffusion of this precursor at 500 K on a hydroxylated silica slab leads to an octahedral-to-square pyramidal rearrangement of its molecular geometry. The free energy profile of the octahedral-to-square pyramidal conversion indicates that the process barrier (5.8 kcal/mol) is of the order of magnitude of the thermal energy at the operating temperature. The formation of hydrogen bonds with surface hydroxyl groups plays a key role in aiding the dissociation of a Zn-O bond. In the square-pyramidal complex, the Zn center has a free coordination position, which might promote the interaction with incoming reagents on the deposition surface. These results provide a valuable atomistic insight on the molecule-to-material conversion process which, in perspective, might help to tailor by design the first nucleation stages of the target ZnO-based nanostructures.

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Graphene adlayer growth between nonepitaxial graphene and Ni(111) substrate: a promising theoretical scheme

Physical Chemistry Chemical Physics ◽

10.1039/d0cp04667a ◽

2020 ◽

Author(s):

Lijuan Meng ◽

Jinlian Lu ◽

Yujie Bai ◽

Lili Liu ◽

Tang Jingyi ◽

...

Keyword(s):

Molecular Dynamics ◽

Density Functional Theory ◽

Chemical Vapor Deposition ◽

Molecular Dynamics Simulations ◽

Vapor Deposition ◽

Density Functional ◽

Chemical Vapor ◽

Density Functional Theory Calculations ◽

Functional Theory ◽

Dynamics Simulations

Understanding the fundamentals of chemical vapor deposition bilayer graphene growth is crucial for its synthesis. By employing density functional theory calculations and classical molecular dynamics simulations, we have investigated the...

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Bonding of Hydrogen and Deuterium in Silicon Nitride Films Prepared by Remote Plasma Enhanced Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-377-313 ◽

1995 ◽

Vol 377 ◽

Cited By ~ 2

Author(s):

G. Stevens ◽

P. Santos-Filho ◽

S. Habermehl ◽

G. Lucovsky

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Reaction Pathway ◽

Total Concentration ◽

Chemical Vapor ◽

Reaction Model ◽

Film Deposition ◽

Growth Surface ◽

Remote Plasma ◽

Silicon Nitride Films

ABSTRACTWe have deposited Si-nitride thin films by remote plasma-enhanced chemical-vapor deposition using different combinations of hydrogen and deuterium source gases. In one set of experiments, NH3 and SiH4 were injected downstream from a He plasma and the ratio of NH3 to SiH4 was adjusted so that deposited films contained IR-detectable bonded-H in SiN-H arrangements, but not in Si-H arrangements. Similar results were obtained using the same ND3 to SiD4 flow ratio; these films contained only SiN-D groups. However, films prepared from ND3 and SiH4 displayed both SiN-D and SiN-H groups in essentially equal concentrations establishing that H and D atoms bonded to N are derived from both source gases SiH (D) 4 and NH (D) 3, and further that inter-mixing of H and/or D atoms occurs at the growth surface. This reaction pathway is supported by additional studies in which films were grown from SD4 and ND3 with either i) He or ii) He/H2 mixtures being plasma excited. The films grown from the deuterated source gases without H2, displayed only SiN-D bands, whereas the films grown using the He/H2 mixture displayed both SiN-H and SiN-D bands. The total concentration of N-H and N-D bonds in the films grown from the He/H2 excitation was the same as the concentration of N-D, supporting the surface reaction model. In-situ mass spectrometry provides additional insights in the film deposition reactions.

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Chemical vapor deposition of layered two-dimensional MoSi2N4 materials

Science ◽

10.1126/science.abb7023 ◽

2020 ◽

Vol 369 (6504) ◽

pp. 670-674 ◽

Cited By ~ 11

Author(s):

Yi-Lun Hong ◽

Zhibo Liu ◽

Lei Wang ◽

Tianya Zhou ◽

Wei Ma ◽

...

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Density Functional ◽

Chemical Vapor ◽

Large Family ◽

Density Functional Theory Calculations ◽

Layered Materials ◽

Molybdenum Nitride ◽

Two Dimensional ◽

Chemical Vapor Deposition Growth

Identifying two-dimensional layered materials in the monolayer limit has led to discoveries of numerous new phenomena and unusual properties. We introduced elemental silicon during chemical vapor deposition growth of nonlayered molybdenum nitride to passivate its surface, which enabled the growth of centimeter-scale monolayer films of MoSi2N4. This monolayer was built up by septuple atomic layers of N-Si-N-Mo-N-Si-N, which can be viewed as a MoN2 layer sandwiched between two Si-N bilayers. This material exhibited semiconducting behavior (bandgap ~1.94 electron volts), high strength (~66 gigapascals), and excellent ambient stability. Density functional theory calculations predict a large family of such monolayer structured two-dimensional layered materials, including semiconductors, metals, and magnetic half-metals.

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Elastic Properties of Several Silicon Nitride Films

MRS Proceedings ◽

10.1557/proc-0989-a22-01 ◽

2007 ◽

Vol 989 ◽

Cited By ~ 6

Author(s):

Xiao Liu ◽

Thomas H Metcalf ◽

Qi Wang ◽

Douglas M Photiadis

Keyword(s):

Chemical Vapor Deposition ◽

Silicon Nitride ◽

Internal Friction ◽

Amorphous Silicon ◽

Elastic Properties ◽

Vapor Deposition ◽

Film Growth ◽

Chemical Vapor ◽

Structural Disorder ◽

Order Of Magnitude

AbstractWe have measured the internal friction (Q-1) of amorphous silicon nitride (a-Si3Nx) films prepared by a variety of methods, including low-pressure chemical-vapor deposition (LPCVD), plasma-enhanced chemical-vapor deposition (PECVD), and hot-wire chemical-vapor deposition (HWCVD) from 0.5 K to room temperature. The measurements are made by depositing the films onto extremely high-Q silicon double paddle oscillator substrates with a resonant frequency of ~5500 Hz. We find the elastic properties of these a-Si3N4 films resemble those of amorphous silicon (a-Si), demonstrating considerable variation, depending on the film growth methods and post deposition annealing. The internal friction for most of the films shows a broad temperature-independent plateau below 30 K, characteristic of amorphous solids. The values of Q-1, however, vary from film to film in this plateau region by more than one order of magnitude. This is typical for tetrehedrally bonded amorphous thin films, like a-Si, a-Ge, and a-C. The PECVD films have the highest Q-1 just like an ordinary amorphous solid, while LPCVD films have an internal friction more than one order of magnitude lower. All the films show a reduction of Q-1 after annealing at 800°C, even for the LPCVD films which were prepared at 850°C. This can be viewed as a reduction of structural disorder.

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Non-Equilibrium Acceptor Concentration in GaN:Mg Grown by Metalorganic Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-798-y5.16 ◽

2003 ◽

Vol 798 ◽

Cited By ~ 2

Author(s):

Y. Gong ◽

Y. Gu ◽

Igor L. Kuskovsky ◽

G. F. Neumark ◽

J. Li ◽

...

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Chemical Vapor ◽

Solubility Limit ◽

Organic Chemical ◽

Original Sample ◽

Acceptor Concentration ◽

Order Of Magnitude ◽

Hall Effect Measurements ◽

Non Equilibrium

ABSTRACTIt is shown that the high p-type conductivity in GaN:Mg, grown by metal-organic chemical vapor deposition followed by post-growth annealing, is due to non-equilibrium acceptor concentrations. A series of samples cut from a single GaN:Mg wafer, which initially had undergone rapid thermal annealing (RTA) after growth, has been investigated. The samples were annealed at various temperatures in nitrogen ambient for over 12 hours, and temperature-dependent Hall effect measurements were performed. For samples annealed at temperatures higher than 850 °C, the hole concentrations decrease by at least an order of magnitude, compared with the original sample. This behavior is explained by an Mg acceptor concentration in excess of its equilibrium solubility limit in the original sample; thus, at high enough temperatures, in the absence of hydrogen, Mg acceptors diffuse either to form electrically inactive precipitates or are eliminated. It is worth noting that the acceptor activation energy remains the same for all samples.

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