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Aravind Asthagiri - One of the best experts on this subject based on the ideXlab platform.
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water adsorption on olivine 010 surfaces effect of alkali and transition metal cation doping
Journal of Chemical Physics, 2019Co-Authors: David R Cole, Aravind AsthagiriAbstract:: Dopants have the potential to locally modify water-olivine interactions, which can impact geological processes, such as weathering, CO2 sequestration, and abiotic hydrocarbon generation. As a first step in understanding the role of Dopants on the water structure and chemistry at water-olivine interfaces, water monomer adsorption on alkaline earth (AE) and transition metal (TM) doped forsterite(010) [Mg2SiO4(010)] surfaces was studied using density functional theory (DFT). Dopants that occur in olivine minerals were considered and consisted of Ca, Sr, and Ba for the AE Dopants and Cr, Mn, Fe, Co, and Ni for the TM Dopants. The water molecule adsorbs on the olivine surface through a metal-water bond (Me-Ow) and a hydrogen bond with an adjacent surface lattice oxygen (Ox-Hw). A frontier orbital analysis reveals that the 1b2, 3a1, and 1b1 (HOMO) of the water molecule are involved in the bonding. All of the TM Dopants show strong net Me-Ow covalent bonding between 3a1 and 1b1 water orbitals and TM d states, while the AE Dopants except for Mg2SiO4(010) show negligible Me-Ow covalent bonding. Both the AE and TM Dopants show similar hydrogen bonding features involving both the 1b2 and 3a1 orbitals. While the AE cations show an overall lower Me-Ow covalent interaction, the AE Dopants have strong electrostatic interactions between the positive metal cation and the negatively charged water dipole. A bonding model incorporating a linear combination of the covalent Me-Ow bond, the Ox-Hw hydrogen bond, the electrostatic interaction between the dopant cation and the H2O molecule, and the surface distortion energy is needed to capture the variation in the DFT adsorption energies on the olivine surfaces. The bonding analysis is able to identify the dominant contributions to water-dopant interactions and can serve as a basis for future studies of more realistic water-olivine interfaces.
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water adsorption on olivine 010 surfaces effect of alkali and transition metal cation doping
Journal of Chemical Physics, 2019Co-Authors: David R Cole, Aravind AsthagiriAbstract:Dopants have the potential to locally modify water-olivine interactions, which can impact geological processes, such as weathering, CO2 sequestration, and abiotic hydrocarbon generation. As a first step in understanding the role of Dopants on the water structure and chemistry at water-olivine interfaces, water monomer adsorption on alkaline earth (AE) and transition metal (TM) doped forsterite(010) [Mg2SiO4(010)] surfaces was studied using density functional theory (DFT). Dopants that occur in olivine minerals were considered and consisted of Ca, Sr, and Ba for the AE Dopants and Cr, Mn, Fe, Co, and Ni for the TM Dopants. The water molecule adsorbs on the olivine surface through a metal-water bond (Me–Ow) and a hydrogen bond with an adjacent surface lattice oxygen (Ox–Hw). A frontier orbital analysis reveals that the 1b2, 3a1, and 1b1 (HOMO) of the water molecule are involved in the bonding. All of the TM Dopants show strong net Me–Ow covalent bonding between 3a1 and 1b1 water orbitals and TM d states, while the AE Dopants except for Mg2SiO4(010) show negligible Me–Ow covalent bonding. Both the AE and TM Dopants show similar hydrogen bonding features involving both the 1b2 and 3a1 orbitals. While the AE cations show an overall lower Me–Ow covalent interaction, the AE Dopants have strong electrostatic interactions between the positive metal cation and the negatively charged water dipole. A bonding model incorporating a linear combination of the covalent Me–Ow bond, the Ox–Hw hydrogen bond, the electrostatic interaction between the dopant cation and the H2O molecule, and the surface distortion energy is needed to capture the variation in the DFT adsorption energies on the olivine surfaces. The bonding analysis is able to identify the dominant contributions to water-dopant interactions and can serve as a basis for future studies of more realistic water-olivine interfaces.Dopants have the potential to locally modify water-olivine interactions, which can impact geological processes, such as weathering, CO2 sequestration, and abiotic hydrocarbon generation. As a first step in understanding the role of Dopants on the water structure and chemistry at water-olivine interfaces, water monomer adsorption on alkaline earth (AE) and transition metal (TM) doped forsterite(010) [Mg2SiO4(010)] surfaces was studied using density functional theory (DFT). Dopants that occur in olivine minerals were considered and consisted of Ca, Sr, and Ba for the AE Dopants and Cr, Mn, Fe, Co, and Ni for the TM Dopants. The water molecule adsorbs on the olivine surface through a metal-water bond (Me–Ow) and a hydrogen bond with an adjacent surface lattice oxygen (Ox–Hw). A frontier orbital analysis reveals that the 1b2, 3a1, and 1b1 (HOMO) of the water molecule are involved in the bonding. All of the TM Dopants show strong net Me–Ow covalent bonding between 3a1 and 1b1 water orbitals and TM d states, wh...
Shinya Aikawa - One of the best experts on this subject based on the ideXlab platform.
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dopant selection for control of charge carrier density and mobility in amorphous indium oxide thin film transistors comparison between si and w Dopants
Applied Physics Letters, 2015Co-Authors: Nobuhiko Mitoma, Shinya Aikawa, Wei Ouyang, Xu Gao, Takio Kizu, Mengfang Lin, Akihiko FujiwaraAbstract:The dependence of oxygen vacancy suppression on dopant species in amorphous indium oxide (a-InOx) thin film transistors (TFTs) is reported. In a-InOx TFTs incorporating equivalent atom densities of Si- and W-Dopants, absorption of oxygen in the host a-InOx matrix was found to depend on difference of Gibbs free energy of the Dopants for oxidation. For fully oxidized films, the extracted channel conductivity was higher in the a-InOx TFTs containing Dopants of small ionic radius. This can be explained by a reduction in the ionic scattering cross sectional area caused by charge screening effects.
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effects of Dopants in inox based amorphous oxide semiconductors for thin film transistor applications
Applied Physics Letters, 2013Co-Authors: Shinya Aikawa, Toshihide Nabatame, Kazuhito TsukagoshiAbstract:Amorphous metal oxide thin-film transistors (TFTs) are fabricated using InOx-based semiconductors doped with TiO2, WO3, or SiO2. Even at low-dopant densities, the electrical properties of the film strongly depend on the dopant used. We found that this dependence could be reasonably explained by differences in the bond-dissociation energy of the Dopants. By incorporating a dopant with a higher bond-dissociation energy, the film became less sensitive to the partial pressure of oxygen used during sputtering and remained electrically stable upon thermal annealing. Thus, choosing a dopant with an appropriate bond-dissociation energy is important when fabricating stable metal-oxide TFTs for flat-panel displays.
Tsujae King Liu - One of the best experts on this subject based on the ideXlab platform.
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effects of oxygen inserted layers on diffusion of boron phosphorus and arsenic in silicon for ultra shallow junction formation
Journal of Applied Physics, 2018Co-Authors: Xi Zhang, Daniel Connelly, H Takeuchi, M Hytha, R J Mears, L Rubin, Tsujae King LiuAbstract:The effects of oxygen-inserted (OI) layers on the diffusion of boron (B), phosphorus (P), and arsenic (As) in silicon (Si) are investigated, for ultra-shallow junction formation by high-dose ion implantation followed by rapid thermal annealing. The projected range (Rp) of the implanted Dopants is shallower than the depth of the OI layers. Secondary ion mass spectrometry is used to compare the dopant profiles in silicon samples that have OI layers against the dopant profiles in control samples that do not have OI layers. Diffusion is found to be substantially retarded by the OI layers for B and P, and less for As, providing shallower junction depth. The experimental results suggest that the OI layers serve to block the diffusion of Si self-interstitials and thereby effectively reduce interstitial-aided diffusion beyond the depth of the OI layers. The OI layers also help to retain more Dopants within the Si, which technology computer-aided design simulations indicate to be beneficial for achieving shallower junctions with lower sheet resistance to enable further miniaturization of planar metal-oxide-semiconductor field-effect transistors for improved integrated-circuit performance and cost per function.The effects of oxygen-inserted (OI) layers on the diffusion of boron (B), phosphorus (P), and arsenic (As) in silicon (Si) are investigated, for ultra-shallow junction formation by high-dose ion implantation followed by rapid thermal annealing. The projected range (Rp) of the implanted Dopants is shallower than the depth of the OI layers. Secondary ion mass spectrometry is used to compare the dopant profiles in silicon samples that have OI layers against the dopant profiles in control samples that do not have OI layers. Diffusion is found to be substantially retarded by the OI layers for B and P, and less for As, providing shallower junction depth. The experimental results suggest that the OI layers serve to block the diffusion of Si self-interstitials and thereby effectively reduce interstitial-aided diffusion beyond the depth of the OI layers. The OI layers also help to retain more Dopants within the Si, which technology computer-aided design simulations indicate to be beneficial for achieving shallower...
David R Cole - One of the best experts on this subject based on the ideXlab platform.
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water adsorption on olivine 010 surfaces effect of alkali and transition metal cation doping
Journal of Chemical Physics, 2019Co-Authors: David R Cole, Aravind AsthagiriAbstract:: Dopants have the potential to locally modify water-olivine interactions, which can impact geological processes, such as weathering, CO2 sequestration, and abiotic hydrocarbon generation. As a first step in understanding the role of Dopants on the water structure and chemistry at water-olivine interfaces, water monomer adsorption on alkaline earth (AE) and transition metal (TM) doped forsterite(010) [Mg2SiO4(010)] surfaces was studied using density functional theory (DFT). Dopants that occur in olivine minerals were considered and consisted of Ca, Sr, and Ba for the AE Dopants and Cr, Mn, Fe, Co, and Ni for the TM Dopants. The water molecule adsorbs on the olivine surface through a metal-water bond (Me-Ow) and a hydrogen bond with an adjacent surface lattice oxygen (Ox-Hw). A frontier orbital analysis reveals that the 1b2, 3a1, and 1b1 (HOMO) of the water molecule are involved in the bonding. All of the TM Dopants show strong net Me-Ow covalent bonding between 3a1 and 1b1 water orbitals and TM d states, while the AE Dopants except for Mg2SiO4(010) show negligible Me-Ow covalent bonding. Both the AE and TM Dopants show similar hydrogen bonding features involving both the 1b2 and 3a1 orbitals. While the AE cations show an overall lower Me-Ow covalent interaction, the AE Dopants have strong electrostatic interactions between the positive metal cation and the negatively charged water dipole. A bonding model incorporating a linear combination of the covalent Me-Ow bond, the Ox-Hw hydrogen bond, the electrostatic interaction between the dopant cation and the H2O molecule, and the surface distortion energy is needed to capture the variation in the DFT adsorption energies on the olivine surfaces. The bonding analysis is able to identify the dominant contributions to water-dopant interactions and can serve as a basis for future studies of more realistic water-olivine interfaces.
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water adsorption on olivine 010 surfaces effect of alkali and transition metal cation doping
Journal of Chemical Physics, 2019Co-Authors: David R Cole, Aravind AsthagiriAbstract:Dopants have the potential to locally modify water-olivine interactions, which can impact geological processes, such as weathering, CO2 sequestration, and abiotic hydrocarbon generation. As a first step in understanding the role of Dopants on the water structure and chemistry at water-olivine interfaces, water monomer adsorption on alkaline earth (AE) and transition metal (TM) doped forsterite(010) [Mg2SiO4(010)] surfaces was studied using density functional theory (DFT). Dopants that occur in olivine minerals were considered and consisted of Ca, Sr, and Ba for the AE Dopants and Cr, Mn, Fe, Co, and Ni for the TM Dopants. The water molecule adsorbs on the olivine surface through a metal-water bond (Me–Ow) and a hydrogen bond with an adjacent surface lattice oxygen (Ox–Hw). A frontier orbital analysis reveals that the 1b2, 3a1, and 1b1 (HOMO) of the water molecule are involved in the bonding. All of the TM Dopants show strong net Me–Ow covalent bonding between 3a1 and 1b1 water orbitals and TM d states, while the AE Dopants except for Mg2SiO4(010) show negligible Me–Ow covalent bonding. Both the AE and TM Dopants show similar hydrogen bonding features involving both the 1b2 and 3a1 orbitals. While the AE cations show an overall lower Me–Ow covalent interaction, the AE Dopants have strong electrostatic interactions between the positive metal cation and the negatively charged water dipole. A bonding model incorporating a linear combination of the covalent Me–Ow bond, the Ox–Hw hydrogen bond, the electrostatic interaction between the dopant cation and the H2O molecule, and the surface distortion energy is needed to capture the variation in the DFT adsorption energies on the olivine surfaces. The bonding analysis is able to identify the dominant contributions to water-dopant interactions and can serve as a basis for future studies of more realistic water-olivine interfaces.Dopants have the potential to locally modify water-olivine interactions, which can impact geological processes, such as weathering, CO2 sequestration, and abiotic hydrocarbon generation. As a first step in understanding the role of Dopants on the water structure and chemistry at water-olivine interfaces, water monomer adsorption on alkaline earth (AE) and transition metal (TM) doped forsterite(010) [Mg2SiO4(010)] surfaces was studied using density functional theory (DFT). Dopants that occur in olivine minerals were considered and consisted of Ca, Sr, and Ba for the AE Dopants and Cr, Mn, Fe, Co, and Ni for the TM Dopants. The water molecule adsorbs on the olivine surface through a metal-water bond (Me–Ow) and a hydrogen bond with an adjacent surface lattice oxygen (Ox–Hw). A frontier orbital analysis reveals that the 1b2, 3a1, and 1b1 (HOMO) of the water molecule are involved in the bonding. All of the TM Dopants show strong net Me–Ow covalent bonding between 3a1 and 1b1 water orbitals and TM d states, wh...
Michiharu Tabe - One of the best experts on this subject based on the ideXlab platform.
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atom devices based on single Dopants in silicon nanostructures
Nanoscale Research Letters, 2011Co-Authors: Daniel Moraru, Takeshi Mizuno, Miftahul Anwar, Ryszard Jablonski, Arief Udhiarto, Roland Nowak, Earfan Hamid, Juli Cha Tarido, Michiharu TabeAbstract:Silicon field-effect transistors have now reached gate lengths of only a few tens of nanometers, containing a countable number of Dopants in the channel. Such technological trend brought us to a research stage on devices working with one or a few dopant atoms. In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism. Furthermore, observation of individual dopant potential in the channel by Kelvin probe force microscopy is also presented. These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.
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Tunable Single-Electron Turnstile Using Discrete Dopants in Nanoscale SOI-FETs
Key Engineering Materials, 2011Co-Authors: Daniel Moraru, Kiyohito Yokoi, R. Nakamura, Sakito Miki, Takeshi Mizuno, Michiharu TabeAbstract:An individual dopant atom may become the active unit of future electronic devices by mediating single-electron transport in nanoscale field-effect transistors. Single Dopants can be accessed electrically even in a dopant-rich environment, offering the opportunity to develop applications based on arrays of Dopants. Here, we focus on single-electron turnstile operation in arrays of dopant-induced quantum dots realized in highly-doped nanoscale transistors. We show that dopant-based single-electron turnstile can be achieved and tuned with a combination of two gates and we indicate guidelines for further optimization.
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single electron transport through single Dopants in a dopant rich environment
Physical Review Letters, 2010Co-Authors: Michiharu Tabe, Daniel Moraru, M Ligowski, Miftahul Anwar, Ryszard Jablonski, Yukinori Ono, Takeshi MizunoAbstract:We show that single-electron transport through a single dopant can be achieved even in a random background of many Dopants without any precise placement of individual Dopants. First, we observe potential maps of a phosphorus-doped channel by low-temperature Kelvin probe force microscopy, and demonstrate potential changes due to single-electron trapping in single Dopants. We then show that only one or a small number of Dopants dominate the initial stage of source-drain current vs gate voltage characteristics in scaled-down, doped-channel, field-effect transistors.