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

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

<p>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 <i>ab initio</i> molecular dynamics (AIMD) in combination with the Bluemoon (BM) statistical sampling approach. AIMD simulations of the Zn β-diketonate-diamine complex Zn(hfa)<sub>2</sub>TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = <i>N</i>,<i>N</i>,<i>N’</i>,<i>N’</i>-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.<b></b></p>

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

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

<p>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 <i>ab initio</i> molecular dynamics (AIMD) in combination with the Bluemoon (BM) statistical sampling approach. AIMD simulations of the Zn β-diketonate-diamine complex Zn(hfa)<sub>2</sub>TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = <i>N</i>,<i>N</i>,<i>N’</i>,<i>N’</i>-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.<b></b></p>

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

2021 ◽  
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 ◽  
Growth Surface ◽  
Surface Hydroxyls ◽  
Order Of Magnitude ◽  
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 dissociation mechanism on the growth surface is not clarified yet. We address this question by Density Functional Theory (DFT) and <i>ab initio</i> molecular dynamics (AIMD) in combination with the Bluemoon (BM) statistical sampling approach. AIMD simulations of the Zn β-diketonate-diamine complex Zn(hfa)<sub>2</sub>TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = <i>N</i>,<i>N</i>,<i>N’</i>,<i>N’</i>-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 magnitude of the thermal energy at the operating temperature. The formation of hydrogen bonds with surface hydroxyls 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.<br>

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

Molecules ◽  
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.

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

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...

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

1995 ◽  
Vol 377 ◽  
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.

Chemical vapor deposition of layered two-dimensional MoSi2N4 materials

Science ◽  
2020 ◽  
Vol 369 (6504) ◽  
pp. 670-674 ◽  
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.

Influence of Hydrogen on Growth of Carbon Nanotubes

2009 ◽  
Vol 1204 ◽  
Author(s):  
Maxim Belov ◽  
Andrey Knizhnik ◽  
Irina Lebedeva ◽  
Alexey Gavrikov ◽  
Boris Potapkin ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional Theory ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Carbon Nanostructures ◽  
Density Functional ◽  
Chemical Vapor ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Thermal Chemical Vapor Deposition

AbstractThe influence of hydrogen on the growth of carbon nanostructures in thermal chemical vapor deposition is studied using density functional theory calculations. It is shown that hydrogen adatoms effectively bind to edges of graphitic structures on the Ni (111) surface. This is found to result in a significant decrease of the rate of carbon attachment to the growing graphitic structures. However, it is also demonstrated that the edges of graphitic structures which are attached to steps on the Ni surface should not be hydrogenated.

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