The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
He Zhou - One of the best experts on this subject based on the ideXlab platform.
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Ti-Ti σ bond at oxygen vacancy inducing the Deep Defect Level in anatase TiO2 (101) surface
The Journal of chemical physics, 2019Co-Authors: Ya-nan Hao, Tingwei Chen, Xiao Zhang, He ZhouAbstract:Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calculated bandgap of the reduced anatase agree well with the experiments. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U.
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ti ti σ bond at oxygen vacancy inducing the Deep Defect Level in anatase tio2 101 surface
Journal of Chemical Physics, 2019Co-Authors: Tingwei Chen, Xiao Zhang, He ZhouAbstract:Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calculated bandgap of the reduced anatase agree well with the experiments. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U.Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty...
Won Kook Choi - One of the best experts on this subject based on the ideXlab platform.
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effects of h 2 annealing treatment on photoluminescence and structure of zno al al2 o 3 grown by radio frequency magnetron sputtering
Journal of The Electrochemical Society, 2003Co-Authors: Jung Cho, Kihyun Yoon, Won Kook ChoiAbstract:Al-doped zinc oxide (AZO) thin films have been grown on Al 2 O 3 (0001) substrate by radio-frequency (rf) magnetron sputtering at 550°C. The AZO films have been annealed by a rapid thermal process in H 2 exposure with a temperature range of 600-1000°C. Effects of hydrogen on the AZO films have been investigated using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The as-grown AZO film shows only broad Deep Defect-Level PL. After annealing at 600°C, Deep Defect-Level emission is quenched and near-band-edge (NBE) emission is observed at around 382 nm (3.2 eV), which can be explained by the H 2 passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emissions have been observed for the first time in annealed AZO thin films. Incorporation of hydrogen and formation of oxygen deficient in annealed AZO films have been studied using XPS. Surface morphology and microstructure of AZO films have been carried out by SEM.
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Effects of H 2 Annealing Treatment on Photoluminescence and Structure of ZnO : Al / Al2 O 3 Grown by Radio-Frequency Magnetron Sputtering
Journal of The Electrochemical Society, 2003Co-Authors: Jung Cho, Kihyun Yoon, Won Kook ChoiAbstract:Al-doped zinc oxide (AZO) thin films have been grown on Al 2 O 3 (0001) substrate by radio-frequency (rf) magnetron sputtering at 550°C. The AZO films have been annealed by a rapid thermal process in H 2 exposure with a temperature range of 600-1000°C. Effects of hydrogen on the AZO films have been investigated using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The as-grown AZO film shows only broad Deep Defect-Level PL. After annealing at 600°C, Deep Defect-Level emission is quenched and near-band-edge (NBE) emission is observed at around 382 nm (3.2 eV), which can be explained by the H 2 passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emissions have been observed for the first time in annealed AZO thin films. Incorporation of hydrogen and formation of oxygen deficient in annealed AZO films have been studied using XPS. Surface morphology and microstructure of AZO films have been carried out by SEM.
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Enhancement of Photoluminescence and Electrical Properties of Ga-Doped ZnO Thin Film Grown on α-Al2O3(0001) Single-Crystal Substrate by rf Magnetron Sputtering through Rapid Thermal Annealing
Japanese Journal of Applied Physics, 2001Co-Authors: Jung Cho, Kihyun Yoon, Jongbum Nah, Jae-hoon Song, Hyung-jin Jung, Won Kook ChoiAbstract:Ga2O3 (1 wt%)-doped ZnO (GZO) thin films were deposited on α-Al2O3(0001) by rf magnetron sputtering at 550°C and a polycrystalline structure was obtained. As-grown GZO thin films show poor electrical properties and photoluminescence (PL). For the improvement of these properties, GZO thin films were annealed at 800–900°C in N2 atmosphere for 3 min. After rapid thermal annealing, Deep-Defect-Level emission disappears and near-band emission is greatly enhanced. Annealed GZO thin films show very low resistivity of 2.6×10-4 Ωcm with 3.9×1020/cm3 carrier concentration and exceptionally high mobility of 60 cm2/Vs. These improved physical properties are explained in terms of the translation of doped-Ga atoms from interstitial to substitutional sites.
Jung Cho - One of the best experts on this subject based on the ideXlab platform.
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effects of h 2 annealing treatment on photoluminescence and structure of zno al al2 o 3 grown by radio frequency magnetron sputtering
Journal of The Electrochemical Society, 2003Co-Authors: Jung Cho, Kihyun Yoon, Won Kook ChoiAbstract:Al-doped zinc oxide (AZO) thin films have been grown on Al 2 O 3 (0001) substrate by radio-frequency (rf) magnetron sputtering at 550°C. The AZO films have been annealed by a rapid thermal process in H 2 exposure with a temperature range of 600-1000°C. Effects of hydrogen on the AZO films have been investigated using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The as-grown AZO film shows only broad Deep Defect-Level PL. After annealing at 600°C, Deep Defect-Level emission is quenched and near-band-edge (NBE) emission is observed at around 382 nm (3.2 eV), which can be explained by the H 2 passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emissions have been observed for the first time in annealed AZO thin films. Incorporation of hydrogen and formation of oxygen deficient in annealed AZO films have been studied using XPS. Surface morphology and microstructure of AZO films have been carried out by SEM.
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Effects of H 2 Annealing Treatment on Photoluminescence and Structure of ZnO : Al / Al2 O 3 Grown by Radio-Frequency Magnetron Sputtering
Journal of The Electrochemical Society, 2003Co-Authors: Jung Cho, Kihyun Yoon, Won Kook ChoiAbstract:Al-doped zinc oxide (AZO) thin films have been grown on Al 2 O 3 (0001) substrate by radio-frequency (rf) magnetron sputtering at 550°C. The AZO films have been annealed by a rapid thermal process in H 2 exposure with a temperature range of 600-1000°C. Effects of hydrogen on the AZO films have been investigated using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The as-grown AZO film shows only broad Deep Defect-Level PL. After annealing at 600°C, Deep Defect-Level emission is quenched and near-band-edge (NBE) emission is observed at around 382 nm (3.2 eV), which can be explained by the H 2 passivation effect. At elevated temperature, two interesting peaks corresponding to violet (406 nm, 3.05 eV) and blue (436 nm, 2.84 eV) emissions have been observed for the first time in annealed AZO thin films. Incorporation of hydrogen and formation of oxygen deficient in annealed AZO films have been studied using XPS. Surface morphology and microstructure of AZO films have been carried out by SEM.
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Enhancement of Photoluminescence and Electrical Properties of Ga-Doped ZnO Thin Film Grown on α-Al2O3(0001) Single-Crystal Substrate by rf Magnetron Sputtering through Rapid Thermal Annealing
Japanese Journal of Applied Physics, 2001Co-Authors: Jung Cho, Kihyun Yoon, Jongbum Nah, Jae-hoon Song, Hyung-jin Jung, Won Kook ChoiAbstract:Ga2O3 (1 wt%)-doped ZnO (GZO) thin films were deposited on α-Al2O3(0001) by rf magnetron sputtering at 550°C and a polycrystalline structure was obtained. As-grown GZO thin films show poor electrical properties and photoluminescence (PL). For the improvement of these properties, GZO thin films were annealed at 800–900°C in N2 atmosphere for 3 min. After rapid thermal annealing, Deep-Defect-Level emission disappears and near-band emission is greatly enhanced. Annealed GZO thin films show very low resistivity of 2.6×10-4 Ωcm with 3.9×1020/cm3 carrier concentration and exceptionally high mobility of 60 cm2/Vs. These improved physical properties are explained in terms of the translation of doped-Ga atoms from interstitial to substitutional sites.
Tingwei Chen - One of the best experts on this subject based on the ideXlab platform.
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Ti-Ti σ bond at oxygen vacancy inducing the Deep Defect Level in anatase TiO2 (101) surface
The Journal of chemical physics, 2019Co-Authors: Ya-nan Hao, Tingwei Chen, Xiao Zhang, He ZhouAbstract:Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calculated bandgap of the reduced anatase agree well with the experiments. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U.
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ti ti σ bond at oxygen vacancy inducing the Deep Defect Level in anatase tio2 101 surface
Journal of Chemical Physics, 2019Co-Authors: Tingwei Chen, Xiao Zhang, He ZhouAbstract:Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calculated bandgap of the reduced anatase agree well with the experiments. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U.Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty...
Xiao Zhang - One of the best experts on this subject based on the ideXlab platform.
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Ti-Ti σ bond at oxygen vacancy inducing the Deep Defect Level in anatase TiO2 (101) surface
The Journal of chemical physics, 2019Co-Authors: Ya-nan Hao, Tingwei Chen, Xiao Zhang, He ZhouAbstract:Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calculated bandgap of the reduced anatase agree well with the experiments. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U.
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ti ti σ bond at oxygen vacancy inducing the Deep Defect Level in anatase tio2 101 surface
Journal of Chemical Physics, 2019Co-Authors: Tingwei Chen, Xiao Zhang, He ZhouAbstract:Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calculated bandgap of the reduced anatase agree well with the experiments. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U.Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of Defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the Deep Defect state in this surface observed experimentally, which is 1 eV below the Fermi Level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the density functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow Defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi Level of anatase near the conduction band bottom. Our GW calculations can explain satisfactorily the coexistence of shallow and Deep Defect states in anatase as observed in experiments. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty...
