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E. P. Skipetrov - One of the best experts on this subject based on the ideXlab platform.
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resonant Impurity Level of ni in the valence band of pb1 xsnxte alloys
Low Temperature Physics, 2021Co-Authors: E. P. Skipetrov, A. V. Knotko, N S Konstantinov, E V Bogdanov, V. E. SlynkoAbstract:The phase and elemental compositions and galvanomagnetic properties (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) of samples from a single-crystal Pb1−x−ySnxNiyTe ingot (x = 0.08, y = 0.01) synthesized by the Bridgman–Stockbarger method were studied. Microscopic inclusions enriched in nickel were found. It is shown that in the main phase, the tin concentration increases exponentially along the ingot (x = 0.06–0.165), while the concentration of nickel Impurity does not exceed 0.4 mol %. A significant increase in the concentration of holes along the ingot and an abnormal increase in the Hall coefficient with increasing temperature were found; both are due to the pinning of the Fermi Level by the resonant nickel Level located in the valence band. The dependences of the hole concentration and of the Fermi energy at T = 4.2 K on the tin concentration in alloys are calculated using the two-band Kane dispersion law. A qualitative model of electronic structure rearrangement is proposed. The model takes into account the movement of the nickel Level into the depth of the valence band with an increase in tin concentration and the redistribution of electrons between the valence band and the Level. The energy position of the nickel Level and the speed of its movement relative to the top of the valence band with an increase in the tin content in Pb1−xSnxTe alloys are estimated.
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Temperature and pressure coefficients of iron resonant Impurity Level in PbTe
Journal of Applied Physics, 2017Co-Authors: E. P. Skipetrov, L. A. Skipetrova, O. V. Kruleveckaya, V. E. SlynkoAbstract:We investigate temperature dependences of galvanomagnetic parameters in weak magnetic fields (4.2 ≤ T ≤ 300 K, B ≤ 0.07 T) in the p-Pb1−yFeyTe alloy from the middle part of the single-crystal ingot, where the Fermi Level is pinned by the resonant Impurity Level lying under the top of the valence band. Experiments are performed under hydrostatic compression up to 10 kbar. Using scanning electron microscopy, we find microscopic inclusions of the secondary phase enriched with iron and show that the main phase is characterized by a good uniformity of the spatial distribution of impurities. A monotonous increase of the free hole concentration at liquid-helium temperature under pressure and anomalous temperature dependences of the Hall coefficient in the whole investigated pressure range are revealed. Experimental results are explained by a model assuming pinning of the Fermi Level by the Impurity Level and a redistribution of electrons between the valence band and Impurity states with increasing temperature an...
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Scandium resonant Impurity Level in PbTe
Journal of Applied Physics, 2014Co-Authors: E. P. Skipetrov, A. V. Knotko, E.i. Slynko, L. A. Skipetrova, V. E. SlynkoAbstract:We synthesize a scandium-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties of Pb1-yScyTe alloys in weak magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) upon varying the scandium content (y ≤ 0.02). We find that all investigated samples are single-phase and n-type. The distribution of scandium impurities along the axis of the ingot is estimated to be exponential. An increase of scandium Impurity content leads to a monotonous growth of the free electron concentration by four orders of magnitude (approximately from 1016 cm−3 to 1020 cm−3). In heavily doped alloys (y > 0.01), the free electron concentration at the liquid-helium temperature tends to saturation, indicating the pinning of the Fermi energy by the scandium resonant Impurity Level located on the background of the conduction band. Using the two-band Kane and six-band Dimmock dispersion relations for IV-VI semiconductors, dependences of the Fermi energy measured from the bott...
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Vanadium deep Impurity Level in diluted magnetic semiconductors Pb1-x-ySnxVyTe
Semiconductors, 2012Co-Authors: E. P. Skipetrov, A. N. Golovanov, A. V. Knotko, E.i. Slynko, V. E. SlynkoAbstract:The crystal structure, Sn and V distribution over the length of single-crystal ingots, and galvanomagnetic effects in low magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) in Pb1−x−y Sn x V y Te alloys (x = 0.05−0.21, y ≤ 0.015) are studied. It is shown that all the samples are single-phase, while the Sn and V concentrations exponentially increase from the beginning to the end of the ingots. Upon doping with V, a decrease in the concentration of free holes and a metal-insulator transition are found. They are related to the appearance of a deep Impurity Level of V in the band gap, electron redistribution between the Level and the valence band, and pinning of the Fermi-Level to the Impurity Level. The shift rate of the V Level relative to the conduction band bottom is determined and a diagram of the reconstruction of the electronic structure of the Pb1 − x − y Sn x V y Te alloy upon varying the host composition is suggested.
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Vanadium deep Impurity Level in diluted magnetic semiconductors Pb_1 − x − y Sn_ x V_ y Te
Semiconductors, 2012Co-Authors: E. P. Skipetrov, A. N. Golovanov, A. V. Knotko, E. I. Slyn’ko, V. E. Slyn’koAbstract:The crystal structure, Sn and V distribution over the length of single-crystal ingots, and galvanomagnetic effects in low magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) in Pb_1− x − y Sn_ x V_ y Te alloys ( x = 0.05−0.21, y ≤ 0.015) are studied. It is shown that all the samples are single-phase, while the Sn and V concentrations exponentially increase from the beginning to the end of the ingots. Upon doping with V, a decrease in the concentration of free holes and a metal-insulator transition are found. They are related to the appearance of a deep Impurity Level of V in the band gap, electron redistribution between the Level and the valence band, and pinning of the Fermi-Level to the Impurity Level. The shift rate of the V Level relative to the conduction band bottom is determined and a diagram of the reconstruction of the electronic structure of the Pb_1 − x − y Sn_ x V_ y Te alloy upon varying the host composition is suggested.
V. E. Slynko - One of the best experts on this subject based on the ideXlab platform.
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resonant Impurity Level of ni in the valence band of pb1 xsnxte alloys
Low Temperature Physics, 2021Co-Authors: E. P. Skipetrov, A. V. Knotko, N S Konstantinov, E V Bogdanov, V. E. SlynkoAbstract:The phase and elemental compositions and galvanomagnetic properties (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) of samples from a single-crystal Pb1−x−ySnxNiyTe ingot (x = 0.08, y = 0.01) synthesized by the Bridgman–Stockbarger method were studied. Microscopic inclusions enriched in nickel were found. It is shown that in the main phase, the tin concentration increases exponentially along the ingot (x = 0.06–0.165), while the concentration of nickel Impurity does not exceed 0.4 mol %. A significant increase in the concentration of holes along the ingot and an abnormal increase in the Hall coefficient with increasing temperature were found; both are due to the pinning of the Fermi Level by the resonant nickel Level located in the valence band. The dependences of the hole concentration and of the Fermi energy at T = 4.2 K on the tin concentration in alloys are calculated using the two-band Kane dispersion law. A qualitative model of electronic structure rearrangement is proposed. The model takes into account the movement of the nickel Level into the depth of the valence band with an increase in tin concentration and the redistribution of electrons between the valence band and the Level. The energy position of the nickel Level and the speed of its movement relative to the top of the valence band with an increase in the tin content in Pb1−xSnxTe alloys are estimated.
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Temperature and pressure coefficients of iron resonant Impurity Level in PbTe
Journal of Applied Physics, 2017Co-Authors: E. P. Skipetrov, L. A. Skipetrova, O. V. Kruleveckaya, V. E. SlynkoAbstract:We investigate temperature dependences of galvanomagnetic parameters in weak magnetic fields (4.2 ≤ T ≤ 300 K, B ≤ 0.07 T) in the p-Pb1−yFeyTe alloy from the middle part of the single-crystal ingot, where the Fermi Level is pinned by the resonant Impurity Level lying under the top of the valence band. Experiments are performed under hydrostatic compression up to 10 kbar. Using scanning electron microscopy, we find microscopic inclusions of the secondary phase enriched with iron and show that the main phase is characterized by a good uniformity of the spatial distribution of impurities. A monotonous increase of the free hole concentration at liquid-helium temperature under pressure and anomalous temperature dependences of the Hall coefficient in the whole investigated pressure range are revealed. Experimental results are explained by a model assuming pinning of the Fermi Level by the Impurity Level and a redistribution of electrons between the valence band and Impurity states with increasing temperature an...
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Scandium resonant Impurity Level in PbTe
Journal of Applied Physics, 2014Co-Authors: E. P. Skipetrov, A. V. Knotko, E.i. Slynko, L. A. Skipetrova, V. E. SlynkoAbstract:We synthesize a scandium-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties of Pb1-yScyTe alloys in weak magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) upon varying the scandium content (y ≤ 0.02). We find that all investigated samples are single-phase and n-type. The distribution of scandium impurities along the axis of the ingot is estimated to be exponential. An increase of scandium Impurity content leads to a monotonous growth of the free electron concentration by four orders of magnitude (approximately from 1016 cm−3 to 1020 cm−3). In heavily doped alloys (y > 0.01), the free electron concentration at the liquid-helium temperature tends to saturation, indicating the pinning of the Fermi energy by the scandium resonant Impurity Level located on the background of the conduction band. Using the two-band Kane and six-band Dimmock dispersion relations for IV-VI semiconductors, dependences of the Fermi energy measured from the bott...
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Vanadium deep Impurity Level in diluted magnetic semiconductors Pb1-x-ySnxVyTe
Semiconductors, 2012Co-Authors: E. P. Skipetrov, A. N. Golovanov, A. V. Knotko, E.i. Slynko, V. E. SlynkoAbstract:The crystal structure, Sn and V distribution over the length of single-crystal ingots, and galvanomagnetic effects in low magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) in Pb1−x−y Sn x V y Te alloys (x = 0.05−0.21, y ≤ 0.015) are studied. It is shown that all the samples are single-phase, while the Sn and V concentrations exponentially increase from the beginning to the end of the ingots. Upon doping with V, a decrease in the concentration of free holes and a metal-insulator transition are found. They are related to the appearance of a deep Impurity Level of V in the band gap, electron redistribution between the Level and the valence band, and pinning of the Fermi-Level to the Impurity Level. The shift rate of the V Level relative to the conduction band bottom is determined and a diagram of the reconstruction of the electronic structure of the Pb1 − x − y Sn x V y Te alloy upon varying the host composition is suggested.
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vanadium induced deep Impurity Level in pb1 xsnxte
Physica B-condensed Matter, 2009Co-Authors: E. P. Skipetrov, A. N. Golovanov, E.i. Slynko, Elena A. Zvereva, V. E. SlynkoAbstract:The galvanomagnetic properties (T=4.2―300 K, B≤0.08T) of Pb 1―x―y Sn x V y Te alloys (x=0.06-0.26, y=0.002-0.066) have been investigated. Low temperature activation range of the Impurity conductivity on the temperature dependencies of resistivity p and of the Hall coefficient R H in the heavily doped samples has been revealed and attributed to the appearance of vanadium-induced deep Level in the gap of the alloys. It was found that in insulating phase alloys possess a high photosensitivity to IR excitation at temperatures up to T c ≈ 40 K. In the alloy with x ≈ 0.2 the metal-insulator transition due to the shift of the Fermi Level from the valence band to the gap with the increase of the vanadium and tin content and the pinning of the Fermi Level by vanadium Level were observed. The diagram of electronic structure reconstruction for Pb 1 ―x―y Sn x V y Te alloys was proposed.
E.i. Slynko - One of the best experts on this subject based on the ideXlab platform.
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Scandium resonant Impurity Level in PbTe
Journal of Applied Physics, 2014Co-Authors: E. P. Skipetrov, A. V. Knotko, E.i. Slynko, L. A. Skipetrova, V. E. SlynkoAbstract:We synthesize a scandium-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties of Pb1-yScyTe alloys in weak magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) upon varying the scandium content (y ≤ 0.02). We find that all investigated samples are single-phase and n-type. The distribution of scandium impurities along the axis of the ingot is estimated to be exponential. An increase of scandium Impurity content leads to a monotonous growth of the free electron concentration by four orders of magnitude (approximately from 1016 cm−3 to 1020 cm−3). In heavily doped alloys (y > 0.01), the free electron concentration at the liquid-helium temperature tends to saturation, indicating the pinning of the Fermi energy by the scandium resonant Impurity Level located on the background of the conduction band. Using the two-band Kane and six-band Dimmock dispersion relations for IV-VI semiconductors, dependences of the Fermi energy measured from the bott...
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Vanadium deep Impurity Level in diluted magnetic semiconductors Pb1-x-ySnxVyTe
Semiconductors, 2012Co-Authors: E. P. Skipetrov, A. N. Golovanov, A. V. Knotko, E.i. Slynko, V. E. SlynkoAbstract:The crystal structure, Sn and V distribution over the length of single-crystal ingots, and galvanomagnetic effects in low magnetic fields (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) in Pb1−x−y Sn x V y Te alloys (x = 0.05−0.21, y ≤ 0.015) are studied. It is shown that all the samples are single-phase, while the Sn and V concentrations exponentially increase from the beginning to the end of the ingots. Upon doping with V, a decrease in the concentration of free holes and a metal-insulator transition are found. They are related to the appearance of a deep Impurity Level of V in the band gap, electron redistribution between the Level and the valence band, and pinning of the Fermi-Level to the Impurity Level. The shift rate of the V Level relative to the conduction band bottom is determined and a diagram of the reconstruction of the electronic structure of the Pb1 − x − y Sn x V y Te alloy upon varying the host composition is suggested.
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vanadium induced deep Impurity Level in pb1 xsnxte
Physica B-condensed Matter, 2009Co-Authors: E. P. Skipetrov, A. N. Golovanov, E.i. Slynko, Elena A. Zvereva, V. E. SlynkoAbstract:The galvanomagnetic properties (T=4.2―300 K, B≤0.08T) of Pb 1―x―y Sn x V y Te alloys (x=0.06-0.26, y=0.002-0.066) have been investigated. Low temperature activation range of the Impurity conductivity on the temperature dependencies of resistivity p and of the Hall coefficient R H in the heavily doped samples has been revealed and attributed to the appearance of vanadium-induced deep Level in the gap of the alloys. It was found that in insulating phase alloys possess a high photosensitivity to IR excitation at temperatures up to T c ≈ 40 K. In the alloy with x ≈ 0.2 the metal-insulator transition due to the shift of the Fermi Level from the valence band to the gap with the increase of the vanadium and tin content and the pinning of the Fermi Level by vanadium Level were observed. The diagram of electronic structure reconstruction for Pb 1 ―x―y Sn x V y Te alloys was proposed.
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Vanadium-induced deep Impurity Level in Pb1−xSnxTe
Physica B-condensed Matter, 2009Co-Authors: E. P. Skipetrov, A. N. Golovanov, E.i. Slynko, Elena A. Zvereva, V. E. SlynkoAbstract:The galvanomagnetic properties (T=4.2―300 K, B≤0.08T) of Pb 1―x―y Sn x V y Te alloys (x=0.06-0.26, y=0.002-0.066) have been investigated. Low temperature activation range of the Impurity conductivity on the temperature dependencies of resistivity p and of the Hall coefficient R H in the heavily doped samples has been revealed and attributed to the appearance of vanadium-induced deep Level in the gap of the alloys. It was found that in insulating phase alloys possess a high photosensitivity to IR excitation at temperatures up to T c ≈ 40 K. In the alloy with x ≈ 0.2 the metal-insulator transition due to the shift of the Fermi Level from the valence band to the gap with the increase of the vanadium and tin content and the pinning of the Fermi Level by vanadium Level were observed. The diagram of electronic structure reconstruction for Pb 1 ―x―y Sn x V y Te alloys was proposed.
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Magnetic properties of Pb1-xGexTe alloys doped with ytterbium
Fifth International Conference on Material Science and Material Properties for Infrared Optoelectronics, 2001Co-Authors: E. P. Skipetrov, L. A. Skipetrova, Natalia A. Chernova, E.i. SlynkoAbstract:fraction of the magnetic centers increases with the increase of the Yb content, but is significantly lower than the total Ybconcentration in the investigated alloys. The obtained results are explained taking into account existing of magnetic Yb3and nonmagnetic Yb2 ions in the alloys and the possibility oftransition of ions from one state to the other due to shift of theYb Impurity Level with respect to the valence band edge as the composition ofthe alloy changes.Keywords: IV-VI semiconductors, magnetic ions, deep Impurity Levels
Lin-wang Wang - One of the best experts on this subject based on the ideXlab platform.
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Shallow Impurity Level calculations in semiconductors using Ab initio methods
Physical Review Letters, 2013Co-Authors: Gaigong Zhang, Andrew Canning, Stephen Derenzo, Niels Gronbech-jensen, Lin-wang WangAbstract:An ab initio method is presented to calculate shallow Impurity Levels in bulk semiconductors. This method combines the GW calculation for the treatment of the central-cell potential with a potential patching method for large systems (with 64 000 atoms) to describe the Impurity state wave functions. The calculated acceptor Levels in Si, GaAs, and an isovalent bound state of GaP are in excellent agreement with experiments with a root-mean-square error of 8.4 meV.
Venkant Venkatasubramanian - One of the best experts on this subject based on the ideXlab platform.
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Neural Network to Understand Process Capability and Process Intermediates Acceptance Criteria in Monoclonal Antibody Production Process
Journal of Pharmaceutical Innovation, 2018Co-Authors: Ying-fei Li, Venkant VenkatasubramanianAbstract:PurposeIn today’s competitive environment, it is crucial for biopharmaceutical companies to have a robust R&D pipeline and reliable manufacturing processes. To ensure success in drug manufacturing, regulatory agencies often mandate appropriate acceptance criteria for process intermediates to increase the likelihood of the drugs meeting the final release specification. When setting acceptance criteria for process intermediates, it is important to first understand process capability, or the Impurity clearance of each process step. However, this process involves either challenging experimentation or an estimation method that might not be comprehensive. In this study, we propose the use of neural network to understand process capability. This approach not only will be able to delineate the relationship between the feed and product Impurity Level for a specific step but will also be able to define the acceptance criteria for the feed (or product from previous process step) Impurity Level based on a predetermined product Impurity Level. These acceptance criteria will enable us to determine whether or not to forward process the step based on the feed Impurity Level.MethodProcess Impurity data are a combination of actual data collected from actual manufacturing lots and simulated data. Impurity clearance for a specific step is estimated using a conventional method and a neural network, a method that we propose in this study.Result and ConclusionSince Impurity clearance is usually dependent on the input Impurity Level, using neural network to estimate process capability and ultimately to define process intermediates acceptance criteria has been shown to be more useful than the conventional method.
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neural network to understand process capability and process intermediates acceptance criteria in monoclonal antibody production process
Journal of Pharmaceutical Innovation, 2018Co-Authors: Venkant VenkatasubramanianAbstract:Purpose In today’s competitive environment, it is crucial for biopharmaceutical companies to have a robust R&D pipeline and reliable manufacturing processes. To ensure success in drug manufacturing, regulatory agencies often mandate appropriate acceptance criteria for process intermediates to increase the likelihood of the drugs meeting the final release specification. When setting acceptance criteria for process intermediates, it is important to first understand process capability, or the Impurity clearance of each process step. However, this process involves either challenging experimentation or an estimation method that might not be comprehensive. In this study, we propose the use of neural network to understand process capability. This approach not only will be able to delineate the relationship between the feed and product Impurity Level for a specific step but will also be able to define the acceptance criteria for the feed (or product from previous process step) Impurity Level based on a predetermined product Impurity Level. These acceptance criteria will enable us to determine whether or not to forward process the step based on the feed Impurity Level.
