Atomic layer deposition process modeling and experimental investigation for sustainable manufacturing of nano thin films
- Pan, Dongqing, Guan, Dongsheng, Jen, Tien-Chien, Yuan, Chris
- Authors: Pan, Dongqing , Guan, Dongsheng , Jen, Tien-Chien , Yuan, Chris
- Date: 2016
- Subjects: Atomic layer deposition; ; , Density functional theory , Sustainability
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/213957 , uj:21218 , Citation: Pan, D. et al. 2016. Atomic layer deposition process modeling and experimental investigation for sustainable manufacturing of nano thin films.
- Description: Abstract: This paper studies the adverse environmental impacts of atomic layer deposition (ALD) nano-manufacturing technology on ALD of Al2O3 nano-scale thin films. Numerical simulations with detailed ALD surface reaction mechanism developed based on Density Functional Theory (DFT), and atomic-level calculations are performed to investigate the effects of four process parameters including process temperature, pulse time, purge time, and carrier gas flow rate on ALD film deposition rate, process emissions and wastes. Full-cycle ALD simulations reveal that the depositions of nano-thin-films in ALD are in essence the chemisorption of the gaseous species and the conversion of surface species. Methane emissions are positively proportional to the film deposition process. The studies show that process temperature fundamentally affects the ALD chemical process by changing the energy states of the surface species. Pulse time is directly related to the precursor dosage. Purge time influences the ALD process by changing the gas-surface interaction time, and higher carrier gas flow rate alters the ALD flow field by accelerating the convective heat and mass transfer in ALD process.
- Full Text:
- Authors: Pan, Dongqing , Guan, Dongsheng , Jen, Tien-Chien , Yuan, Chris
- Date: 2016
- Subjects: Atomic layer deposition; ; , Density functional theory , Sustainability
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/213957 , uj:21218 , Citation: Pan, D. et al. 2016. Atomic layer deposition process modeling and experimental investigation for sustainable manufacturing of nano thin films.
- Description: Abstract: This paper studies the adverse environmental impacts of atomic layer deposition (ALD) nano-manufacturing technology on ALD of Al2O3 nano-scale thin films. Numerical simulations with detailed ALD surface reaction mechanism developed based on Density Functional Theory (DFT), and atomic-level calculations are performed to investigate the effects of four process parameters including process temperature, pulse time, purge time, and carrier gas flow rate on ALD film deposition rate, process emissions and wastes. Full-cycle ALD simulations reveal that the depositions of nano-thin-films in ALD are in essence the chemisorption of the gaseous species and the conversion of surface species. Methane emissions are positively proportional to the film deposition process. The studies show that process temperature fundamentally affects the ALD chemical process by changing the energy states of the surface species. Pulse time is directly related to the precursor dosage. Purge time influences the ALD process by changing the gas-surface interaction time, and higher carrier gas flow rate alters the ALD flow field by accelerating the convective heat and mass transfer in ALD process.
- Full Text:
Influence of single and double-atom metal doping on the electrocatalytic hydrogen evolution activity of 2D-MoS2 surface
- Mohlala, Lesego M., Oviroh, Peter O., Jen, Tien-Chien, Olubambi, Peter A.
- Authors: Mohlala, Lesego M. , Oviroh, Peter O. , Jen, Tien-Chien , Olubambi, Peter A.
- Date: 2020
- Subjects: Atomic doping , Density functional theory , Hydrogen evolution reaction
- Language: English
- Type: Conference Proceedings
- Identifier: http://hdl.handle.net/10210/461510 , uj:41110 , Citation: Mohlala, L.M. et al. 2020. Influence of single and double-atom metal doping on the electrocatalytic hydrogen evolution activity of 2D-MoS2 surface.
- Description: Abstract: The Hydrogen evolution reaction (HER) is an important process during electrocatalytic water splitting for hydrogen energy generation. Two dimensional (2D) MoS2 has been considered as a promising alternative to Pt-based catalysts in the hydrogen evolution reaction. However, the highest contribution for the catalytic activity of 2D-MoS2 is from its edge sites, this in turn leaves many in-plane domains useless. In this study, the effect of single atom metal (Pt, Ni and Pt-Ni) doping on HER catalytic activity of in-plane atoms was investigated using density functional theory calculations. The Gibbs free energy of adsorbed hydrogen on pristine MoS2 decreased from 1.86eV to -0.08eV in PtNi co-doped MoS2. This demonstrates enhanced catalytic activity of MoS2 due to atomic doping. The enhanced catalytic activity may also be attributed to the observed changes and increase in the density of electronic states near the Fermi energy level.
- Full Text:
- Authors: Mohlala, Lesego M. , Oviroh, Peter O. , Jen, Tien-Chien , Olubambi, Peter A.
- Date: 2020
- Subjects: Atomic doping , Density functional theory , Hydrogen evolution reaction
- Language: English
- Type: Conference Proceedings
- Identifier: http://hdl.handle.net/10210/461510 , uj:41110 , Citation: Mohlala, L.M. et al. 2020. Influence of single and double-atom metal doping on the electrocatalytic hydrogen evolution activity of 2D-MoS2 surface.
- Description: Abstract: The Hydrogen evolution reaction (HER) is an important process during electrocatalytic water splitting for hydrogen energy generation. Two dimensional (2D) MoS2 has been considered as a promising alternative to Pt-based catalysts in the hydrogen evolution reaction. However, the highest contribution for the catalytic activity of 2D-MoS2 is from its edge sites, this in turn leaves many in-plane domains useless. In this study, the effect of single atom metal (Pt, Ni and Pt-Ni) doping on HER catalytic activity of in-plane atoms was investigated using density functional theory calculations. The Gibbs free energy of adsorbed hydrogen on pristine MoS2 decreased from 1.86eV to -0.08eV in PtNi co-doped MoS2. This demonstrates enhanced catalytic activity of MoS2 due to atomic doping. The enhanced catalytic activity may also be attributed to the observed changes and increase in the density of electronic states near the Fermi energy level.
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