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Roel Van De Krol - One of the best experts on this subject based on the ideXlab platform.
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Influence of point defects on the performance of InVO4 photoanodes
Journal of Photonics for Energy, 2011Co-Authors: Roel Van De Krol, Julie Ségalini, Cristina S. EnacheAbstract:The properties of thin film InVO4 photoanodes for water splitting have been studied. Compact films of InVO4 were prepared by spray pyrolysis and are found to be stable between pH 3 and 11. Although the indirect bandgap is 3.2 eV, a modest amount of visible light absorption is observed. The origin of this absorption is attributed to the presence of Deep Donor states at ?0.7 eV below the conduction band. These Donor states presumably correspond to oxygen vacancies, which form as a result of small but unavoidable deviations of In:V from the ideal 1:1 stoichiometry during the wet-chemical synthesis process. Shallow Donors are absent in this material, in contrast to what is normally observed for metal oxides. The Deep Donor model explains the much stronger visible light absorption of powders compared to thin films. The defect chemical reactions that lead to the formation of the Deep Donors are shown, and are supported by photoluminescence data
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Influence of point defects on the performance of InVO4 photoanodes
Solar Hydrogen and Nanotechnology V, 2010Co-Authors: Roel Van De Krol, Julie Ségalini, Cristina S. EnacheAbstract:The properties of thin film InVO4 photoanodes for water splitting have been studied. Compact films of InVO4 were prepared by spray pyrolysis and are found to be stable between pH 3 – 11. Although the indirect bandgap is 3.2 eV, a modest amount of visible light absorption is observed. The origin of this absorption is attributed to the presence of Deep Donor states at ~0.7 eV below the conduction band. Shallow Donors are absent in this material, in contrast to what is normally observed for metal oxides. The Deep Donor model explains the much stronger visible light absorption of powders compared to thin films, and is supported by photoluminescence data. The origin of the Deep Donors is attributed to deviations in the In:V ratio, and the corresponding defect-chemical reactions will be discussed.
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Photo-electrochemical Properties of Thin-Film InVO4 Photoanodes: the Role of Deep Donor States
The Journal of Physical Chemistry C, 2009Co-Authors: Cristina S. Enache, David C. Lloyd, Martijn R. Damen, Joop Schoonman, Roel Van De KrolAbstract:The material properties and photoelectrochemical performance of compact thin-film InVO4 photoanodes prepared by spray pyrolysis are investigated. Nearly phase-pure orthorhombic InVO4 can be obtained by a postdeposition anneal treatment in air between 450−550 °C. Optical absorption spectra indicate that InVO4 has an indirect bandgap of ∼3.2 eV with a pronounced sub-bandgap absorption starting at ∼2.5 eV. A dielectric constant of 50 and a flatband potential of −0.04 V vs RHE are determined, which confirms that this material is able to evolve hydrogen. Few shallow Donors are present in this material, which is markedly different from what is usually observed for simple binary oxides. The main photocurrent response occurs in the UV (
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photo electrochemical properties of thin film invo4 photoanodes the role of Deep Donor states
Journal of Physical Chemistry C, 2009Co-Authors: Cristina S. Enache, David C. Lloyd, Martijn R. Damen, Joop Schoonman, Roel Van De KrolAbstract:The material properties and photoelectrochemical performance of compact thin-film InVO4 photoanodes prepared by spray pyrolysis are investigated. Nearly phase-pure orthorhombic InVO4 can be obtained by a postdeposition anneal treatment in air between 450−550 °C. Optical absorption spectra indicate that InVO4 has an indirect bandgap of ∼3.2 eV with a pronounced sub-bandgap absorption starting at ∼2.5 eV. A dielectric constant of 50 and a flatband potential of −0.04 V vs RHE are determined, which confirms that this material is able to evolve hydrogen. Few shallow Donors are present in this material, which is markedly different from what is usually observed for simple binary oxides. The main photocurrent response occurs in the UV (<400 nm) and the incident photon-to-current conversion efficiency is less than 1%. The impedance data show that the poor photo response is due to a high density of Deep Donors and a concomitantly small depletion layer. The visible light absorption of InVO4 is attributed to the pres...
Cristina S. Enache - One of the best experts on this subject based on the ideXlab platform.
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Influence of point defects on the performance of InVO4 photoanodes
Journal of Photonics for Energy, 2011Co-Authors: Roel Van De Krol, Julie Ségalini, Cristina S. EnacheAbstract:The properties of thin film InVO4 photoanodes for water splitting have been studied. Compact films of InVO4 were prepared by spray pyrolysis and are found to be stable between pH 3 and 11. Although the indirect bandgap is 3.2 eV, a modest amount of visible light absorption is observed. The origin of this absorption is attributed to the presence of Deep Donor states at ?0.7 eV below the conduction band. These Donor states presumably correspond to oxygen vacancies, which form as a result of small but unavoidable deviations of In:V from the ideal 1:1 stoichiometry during the wet-chemical synthesis process. Shallow Donors are absent in this material, in contrast to what is normally observed for metal oxides. The Deep Donor model explains the much stronger visible light absorption of powders compared to thin films. The defect chemical reactions that lead to the formation of the Deep Donors are shown, and are supported by photoluminescence data
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Influence of point defects on the performance of InVO4 photoanodes
Solar Hydrogen and Nanotechnology V, 2010Co-Authors: Roel Van De Krol, Julie Ségalini, Cristina S. EnacheAbstract:The properties of thin film InVO4 photoanodes for water splitting have been studied. Compact films of InVO4 were prepared by spray pyrolysis and are found to be stable between pH 3 – 11. Although the indirect bandgap is 3.2 eV, a modest amount of visible light absorption is observed. The origin of this absorption is attributed to the presence of Deep Donor states at ~0.7 eV below the conduction band. Shallow Donors are absent in this material, in contrast to what is normally observed for metal oxides. The Deep Donor model explains the much stronger visible light absorption of powders compared to thin films, and is supported by photoluminescence data. The origin of the Deep Donors is attributed to deviations in the In:V ratio, and the corresponding defect-chemical reactions will be discussed.
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Photo-electrochemical Properties of Thin-Film InVO4 Photoanodes: the Role of Deep Donor States
The Journal of Physical Chemistry C, 2009Co-Authors: Cristina S. Enache, David C. Lloyd, Martijn R. Damen, Joop Schoonman, Roel Van De KrolAbstract:The material properties and photoelectrochemical performance of compact thin-film InVO4 photoanodes prepared by spray pyrolysis are investigated. Nearly phase-pure orthorhombic InVO4 can be obtained by a postdeposition anneal treatment in air between 450−550 °C. Optical absorption spectra indicate that InVO4 has an indirect bandgap of ∼3.2 eV with a pronounced sub-bandgap absorption starting at ∼2.5 eV. A dielectric constant of 50 and a flatband potential of −0.04 V vs RHE are determined, which confirms that this material is able to evolve hydrogen. Few shallow Donors are present in this material, which is markedly different from what is usually observed for simple binary oxides. The main photocurrent response occurs in the UV (
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photo electrochemical properties of thin film invo4 photoanodes the role of Deep Donor states
Journal of Physical Chemistry C, 2009Co-Authors: Cristina S. Enache, David C. Lloyd, Martijn R. Damen, Joop Schoonman, Roel Van De KrolAbstract:The material properties and photoelectrochemical performance of compact thin-film InVO4 photoanodes prepared by spray pyrolysis are investigated. Nearly phase-pure orthorhombic InVO4 can be obtained by a postdeposition anneal treatment in air between 450−550 °C. Optical absorption spectra indicate that InVO4 has an indirect bandgap of ∼3.2 eV with a pronounced sub-bandgap absorption starting at ∼2.5 eV. A dielectric constant of 50 and a flatband potential of −0.04 V vs RHE are determined, which confirms that this material is able to evolve hydrogen. Few shallow Donors are present in this material, which is markedly different from what is usually observed for simple binary oxides. The main photocurrent response occurs in the UV (<400 nm) and the incident photon-to-current conversion efficiency is less than 1%. The impedance data show that the poor photo response is due to a high density of Deep Donors and a concomitantly small depletion layer. The visible light absorption of InVO4 is attributed to the pres...
R Stein - One of the best experts on this subject based on the ideXlab platform.
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infrared spectra and electron spin resonance of vanadium Deep level impurities in silicon carbide
Applied Physics Letters, 1990Co-Authors: J. Schneider, H D Muller, K Maier, W Wilkening, F Fuchs, A Dornen, S Leibenzeder, R SteinAbstract:Trace impurities of vanadium in Lely‐grown silicon carbide single crystals have been detected by their strong, polytype‐specific photoluminescence in the 1.3–1.5 μm near‐infrared spectral range, as well as by infrared absorption. The spectra arise from the intra‐3d‐shell transitions 2E(3d1)→2T2(3d1) of V4+Si(3d1). Electron spin resonance reveals that VSi in SiC acts as a Deep acceptor, V4+Si(3d1)/V3+Si(3d2)−A0/A−, and possibly also as a Deep Donor. The role of vanadium as minority‐carrier lifetime killer in SiC‐based optoelectronic devices is suggested from these data.
J. Schneider - One of the best experts on this subject based on the ideXlab platform.
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Deep Donor state of vanadium in cubic silicon carbide (3C‐SiC)
Applied Physics Letters, 1994Co-Authors: K. F. Dombrowski, Ulrich Kaufmann, Michael Kunzer, Karin Maier, J. Schneider, V. B. Shields, Michael G. SpencerAbstract:Electron spin resonance (ESR) of silicon‐substitutional vanadium in its neutral V4+Si (3d1) state has been observed in cubic bulk 3C‐SiC single crystals. By photo‐ESR the position of the (0/+) Deep Donor level of vanadium could be located at EV+1.7 eV. Using this level as common reference in 3C‐SiC and 6H‐SiC, the valence‐band discontinuity in the 3C‐SiC/6H‐SiC interface is predicted as ΔEV=0.1 eV, with the valence band of 3C‐SiC lying lower in energy. We also offer an explanation for the absence of intra‐3d‐shell infrared luminescence of V4+ (3d1) in 3C‐SiC.
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infrared spectra and electron spin resonance of vanadium Deep level impurities in silicon carbide
Applied Physics Letters, 1990Co-Authors: J. Schneider, H D Muller, K Maier, W Wilkening, F Fuchs, A Dornen, S Leibenzeder, R SteinAbstract:Trace impurities of vanadium in Lely‐grown silicon carbide single crystals have been detected by their strong, polytype‐specific photoluminescence in the 1.3–1.5 μm near‐infrared spectral range, as well as by infrared absorption. The spectra arise from the intra‐3d‐shell transitions 2E(3d1)→2T2(3d1) of V4+Si(3d1). Electron spin resonance reveals that VSi in SiC acts as a Deep acceptor, V4+Si(3d1)/V3+Si(3d2)−A0/A−, and possibly also as a Deep Donor. The role of vanadium as minority‐carrier lifetime killer in SiC‐based optoelectronic devices is suggested from these data.
David C. Look - One of the best experts on this subject based on the ideXlab platform.
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Nonalloyed ohmic contacts on low‐temperature molecular beam epitaxial GaAs: Influence of Deep Donor band
Applied Physics Letters, 1990Co-Authors: H. Yamamoto, Z-q. Fang, David C. LookAbstract:The Ohmic nature of the nonalloyed metal contact on molecular beam epitaxial GaAs grown at 200 °C was studied. The specific contact resistances at room temperature and 120 K were 1.5×10−3 and 7.0×10−1 Ω cm2, respectively. These values are anomalously low considering that the conduction‐band electron concentration in this material is less than 1011 cm−3 at room temperature. The experimental results indicate that the carrier transport at the metal/semiconductor interface is dominated by a dense (∼3×1019 cm−3) EL2‐like Deep Donor band, rather than the usual conduction band.
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nonalloyed ohmic contacts on low temperature molecular beam epitaxial gaas influence of Deep Donor band
Applied Physics Letters, 1990Co-Authors: H. Yamamoto, Z-q. Fang, David C. LookAbstract:The Ohmic nature of the nonalloyed metal contact on molecular beam epitaxial GaAs grown at 200 °C was studied. The specific contact resistances at room temperature and 120 K were 1.5×10−3 and 7.0×10−1 Ω cm2, respectively. These values are anomalously low considering that the conduction‐band electron concentration in this material is less than 1011 cm−3 at room temperature. The experimental results indicate that the carrier transport at the metal/semiconductor interface is dominated by a dense (∼3×1019 cm−3) EL2‐like Deep Donor band, rather than the usual conduction band.
