Cette invention concerne un procede de commande d'un processus de purification d'un mater... more Cette invention concerne un procede de commande d'un processus de purification d'un materiau Si-UMG en effectuant une solidification directionnelle de Si-UMG fondu pour obtenir un lingot de silicium. Le lingot est divise en briques et le profil de resistivite de chaque brique de silicium est cartographie. Un repere de recadrage permettant d'eliminer les impuretes concentrees et capturees dans le lingot durant la solidification directionnelle est calcule d'apres la cartographie de la resistivite. Les impuretes concentrees sont ensuite eliminees en recadrant chaque brique par rapport au repere de recadrage calcule pour ladite brique.
Calcium aluminate slag produced by the aluminothermic reduction of silica is tested as a candidat... more Calcium aluminate slag produced by the aluminothermic reduction of silica is tested as a candidate raw material for the hydrometallurgical production of pure aluminium chloride hexahydrate (ACH) through leaching with hydrochloric acid. The crystallization of ACH follows by sparging the pregnant liquor with hydrochloric gas. Almost total extraction of Al is achieved with the use of azeotropic HCl acid solution (5.9 M) at 80 °C and 1 h retention time. A pregnant liquor with approximately 20 wt% AlCl3 is produced as a base for ACH crystallization by sparging it with gaseous HCl. The ACH produced is re-dissolved and crystallized three to four times until high purity is achieved. High purity ACH acts as a precursor for producing High Purity Alumina (HPA), a high added value material used in LEDs and lithium-ion batteries and other niche applications.
CaFeo.52O6Si2Zno.48, monoclinic, C\21c\ (No. 15), a = 9.8206(8) À, b = 8.9966(8)Â, c = 5 . 2 4 8 ... more CaFeo.52O6Si2Zno.48, monoclinic, C\21c\ (No. 15), a = 9.8206(8) À, b = 8.9966(8)Â, c = 5 . 2 4 8 7 ( 4 ) K ß = 105.34(1)°, V = 447.2 Â*, Ζ = 4, RffíF) = 0.029, w R ^ F 2 ) = 0.067, Τ = 293 Κ. Source of material Single crystals of Cao.98(2)Feo.59(3)Zno.46(3)Sii.98(2)C>6 were obtained under high pressure and high temperature conditions. Starting with a stoichiometric mixture of oxides (purity > 99.999%) the synthesis was performed in a Piston-Cylinder apparatus over 65 hours with a temperature of 1123 Κ and a pressure of 1.8 GPa. The chemical composition of the crystal was determined by e lectron microprobe ( C A M E C A S X 5 0 , 15 kV/20 nA, standards: wollastonite CaSiC>3, hematite Fe2C>3, and sphalerite ZnS). Discussion The investigated material has a clinopyroxene structure [1] in which Zn shares the M1 position with Fe. The M2 site is completely occupied by Ca. In the most structures, zinc is tetrahedrally coordinated [2,3] and the octahedral coordination of zinc in ...
In this study, synchrotron-based x-ray absorption microspectroscopy (mu-XAS) is applied to identi... more In this study, synchrotron-based x-ray absorption microspectroscopy (mu-XAS) is applied to identifying the chemical states of copper-rich clusters within a variety of silicon materials, including as-grown cast multicrystalline silicon solar cell material with high oxygen concentration and other silicon materials with varying degrees of oxygen concentration and copper contamination pathways. In all samples, copper silicide (Cu3Si) is the only phase
Physical Review B Condensed Matter and Materials Physics, Jun 1, 2006
We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, a... more We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, and Si, found as precipitates in multicrystalline silicon. The analysis of extended x-ray absorption fine-structure microspectroscopy (μ-EXAFS) measurements on the K edges of ...
Lawrence Berkeley National Laboratory, Nov 8, 2004
Synchrotron-based microprobe techniques were used to obtain precise and systematic information ab... more Synchrotron-based microprobe techniques were used to obtain precise and systematic information about the size distribution, spatial distribution, shape, electrical activity, and chemical states of iron-rich impurity clusters in multicrystalline silicon materials used for cost-effective solar cells. These experimentally observed properties of iron-rich clusters allow one to derive conclusions about the origins of iron contamination, the mechanisms for incorporating large amounts
ABSTRACT The present invention relates to the internal gettering of impurities in semiconductors ... more ABSTRACT The present invention relates to the internal gettering of impurities in semiconductors by metal alloy clusters. In particular, intermetallic clusters are formed within silicon, such clusters containing two or more transition metal species. Such clusters have melting temperatures below that of the host material and are shown to be particularly effective in gettering impurities within the silicon and collecting them into isolated, less harmful locations. Novel compositions for some of the metal alloy clusters are also described.
the chemical state and distribution of Cu-rich clusters were determined in four different silicon... more the chemical state and distribution of Cu-rich clusters were determined in four different silicon-based materials with varying contamination pathways and degrees of oxygen concentration, including as-grown multicrystalline silicon. In all four samples, Cu3Si was the only chemical state observed. Cu3Si clusters were observed at structural defects within all four materials; XBIC measurements revealed that the presence of Cu3Si corresponds to increased recombination activity. Oxidized Cu compounds are not likely to form in silicon. The +1 eV edge shift in the -XAS absorption spectrum of Cu3Si relative to Cu metal is believed to be an indication of a degree of covalent bonding between Cu atoms and their silicon neighbors.
the chemical state and distribution of Cu-rich clusters were determined in four different silicon... more the chemical state and distribution of Cu-rich clusters were determined in four different silicon-based materials with varying contamination pathways and degrees of oxygen concentration, including as-grown multicrystalline silicon. In all four samples, Cu3Si was the only chemical state observed. Cu3Si clusters were observed at structural defects within all four materials; XBIC measurements revealed that the presence of Cu3Si corresponds to increased recombination activity. Oxidized Cu compounds are not likely to form in silicon. The +1 eV edge shift in the -XAS absorption spectrum of Cu3Si relative to Cu metal is believed to be an indication of a degree of covalent bonding between Cu atoms and their silicon neighbors.
X-ray fluorescence microscopy (mu-XRF), x-ray beam induced current (XBIC), and x-ray absorption s... more X-ray fluorescence microscopy (mu-XRF), x-ray beam induced current (XBIC), and x-ray absorption spectromicroscopy (mu-XAS) were performed on fully-processed Bay Six cast multicrystalline silicon and aluminum-gettered AstroPower Silicon-Film(TM) sheet material. Over ten iron precipitates--predominantly of iron silicide--were identified at low lifetime regions in both materials, both at grain boundaries and intragranular defects identified by XBIC. In addition, large (micron-sized) particles containing oxidized iron and other impurities (Ca, Cr, Mn) were found in BaySix material. The smaller iron silicide precipitates were more numerous and spatially distributed than their larger oxidized iron counterparts, and thus deemed more detrimental to minority carrier diffusion length.
ABSTRACT Synchrotron-based microprobe techniques have been applied to study the distribution, siz... more ABSTRACT Synchrotron-based microprobe techniques have been applied to study the distribution, size, chemical state, and recombination activity of Fe clusters in two types of mc-Si materials: block cast mc-Si, and AstroPower Silicon Film(TM) sheet material. In sheet material, high concentrations of metals were found at recombination-active, micron-sized intragranular clusters consisting of micron and sub-micron sized particles. In addition, Fe nanoparticles were located in densities of â2'107 cm-2 along recombination-active grain boundaries. In cast mc-Si,two types of particles were identified at grain boundaries: (1) micron-sized oxidized Fe particles accompanied by other metals (Cr, Mn, Ca, Ti), and (2) a higher number of sub-micron FeSi2 precipitates that exhibited a preferred orientation along the crystal growth direction. In both materials, it is believed that the larger Fe clusters are inclusions of foreign particles, from which Fe dissolves in the melt to form the smaller FeSi2 nanoprecipitates, which by virtue of their more homogeneous distribution are deemed more dangerous to solar cell device performance. Based on this understanding, strategies proposed to reduce the impact of Fe on mc-Si electrical properties include gettering, passivation, and limiting the dissolution of foreign Fe-rich particles in the melt.
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005., 2005
... Tonio Buonassisi'.', Andrei A. Istratov"2, Matthew A. ... more ... Tonio Buonassisi'.', Andrei A. Istratov"2, Matthew A. Marcus'*3, Stefan Peters4; Christophe BalliPt, Matthias Heuer5, Ted F. Ciszek6, Zhonghou Cai', Bany Lai', Roland Schindler , ficke R. Webe?" Lawrence Berkeley National Laboratory, Berkeley, CA; 'Department of Materials ...
A high flux, non-destructive X-ray synchrotron-based technique, X-ray fluorescence microscopy (μ-... more A high flux, non-destructive X-ray synchrotron-based technique, X-ray fluorescence microscopy (μ-XRF), is able to detect metal precipitates as small as a few tens of nanometers in diameter within a silicon matrix, with micron-scale spatial resolution. When ...
We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, a... more We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, and Si, found as precipitates in multicrystalline silicon. The analysis of extended x-ray absorption fine-structure microspectroscopy (μ-EXAFS) measurements on the K edges of ...
Cette invention concerne un procede de commande d'un processus de purification d'un mater... more Cette invention concerne un procede de commande d'un processus de purification d'un materiau Si-UMG en effectuant une solidification directionnelle de Si-UMG fondu pour obtenir un lingot de silicium. Le lingot est divise en briques et le profil de resistivite de chaque brique de silicium est cartographie. Un repere de recadrage permettant d'eliminer les impuretes concentrees et capturees dans le lingot durant la solidification directionnelle est calcule d'apres la cartographie de la resistivite. Les impuretes concentrees sont ensuite eliminees en recadrant chaque brique par rapport au repere de recadrage calcule pour ladite brique.
Calcium aluminate slag produced by the aluminothermic reduction of silica is tested as a candidat... more Calcium aluminate slag produced by the aluminothermic reduction of silica is tested as a candidate raw material for the hydrometallurgical production of pure aluminium chloride hexahydrate (ACH) through leaching with hydrochloric acid. The crystallization of ACH follows by sparging the pregnant liquor with hydrochloric gas. Almost total extraction of Al is achieved with the use of azeotropic HCl acid solution (5.9 M) at 80 °C and 1 h retention time. A pregnant liquor with approximately 20 wt% AlCl3 is produced as a base for ACH crystallization by sparging it with gaseous HCl. The ACH produced is re-dissolved and crystallized three to four times until high purity is achieved. High purity ACH acts as a precursor for producing High Purity Alumina (HPA), a high added value material used in LEDs and lithium-ion batteries and other niche applications.
CaFeo.52O6Si2Zno.48, monoclinic, C\21c\ (No. 15), a = 9.8206(8) À, b = 8.9966(8)Â, c = 5 . 2 4 8 ... more CaFeo.52O6Si2Zno.48, monoclinic, C\21c\ (No. 15), a = 9.8206(8) À, b = 8.9966(8)Â, c = 5 . 2 4 8 7 ( 4 ) K ß = 105.34(1)°, V = 447.2 Â*, Ζ = 4, RffíF) = 0.029, w R ^ F 2 ) = 0.067, Τ = 293 Κ. Source of material Single crystals of Cao.98(2)Feo.59(3)Zno.46(3)Sii.98(2)C>6 were obtained under high pressure and high temperature conditions. Starting with a stoichiometric mixture of oxides (purity > 99.999%) the synthesis was performed in a Piston-Cylinder apparatus over 65 hours with a temperature of 1123 Κ and a pressure of 1.8 GPa. The chemical composition of the crystal was determined by e lectron microprobe ( C A M E C A S X 5 0 , 15 kV/20 nA, standards: wollastonite CaSiC>3, hematite Fe2C>3, and sphalerite ZnS). Discussion The investigated material has a clinopyroxene structure [1] in which Zn shares the M1 position with Fe. The M2 site is completely occupied by Ca. In the most structures, zinc is tetrahedrally coordinated [2,3] and the octahedral coordination of zinc in ...
In this study, synchrotron-based x-ray absorption microspectroscopy (mu-XAS) is applied to identi... more In this study, synchrotron-based x-ray absorption microspectroscopy (mu-XAS) is applied to identifying the chemical states of copper-rich clusters within a variety of silicon materials, including as-grown cast multicrystalline silicon solar cell material with high oxygen concentration and other silicon materials with varying degrees of oxygen concentration and copper contamination pathways. In all samples, copper silicide (Cu3Si) is the only phase
Physical Review B Condensed Matter and Materials Physics, Jun 1, 2006
We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, a... more We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, and Si, found as precipitates in multicrystalline silicon. The analysis of extended x-ray absorption fine-structure microspectroscopy (μ-EXAFS) measurements on the K edges of ...
Lawrence Berkeley National Laboratory, Nov 8, 2004
Synchrotron-based microprobe techniques were used to obtain precise and systematic information ab... more Synchrotron-based microprobe techniques were used to obtain precise and systematic information about the size distribution, spatial distribution, shape, electrical activity, and chemical states of iron-rich impurity clusters in multicrystalline silicon materials used for cost-effective solar cells. These experimentally observed properties of iron-rich clusters allow one to derive conclusions about the origins of iron contamination, the mechanisms for incorporating large amounts
ABSTRACT The present invention relates to the internal gettering of impurities in semiconductors ... more ABSTRACT The present invention relates to the internal gettering of impurities in semiconductors by metal alloy clusters. In particular, intermetallic clusters are formed within silicon, such clusters containing two or more transition metal species. Such clusters have melting temperatures below that of the host material and are shown to be particularly effective in gettering impurities within the silicon and collecting them into isolated, less harmful locations. Novel compositions for some of the metal alloy clusters are also described.
the chemical state and distribution of Cu-rich clusters were determined in four different silicon... more the chemical state and distribution of Cu-rich clusters were determined in four different silicon-based materials with varying contamination pathways and degrees of oxygen concentration, including as-grown multicrystalline silicon. In all four samples, Cu3Si was the only chemical state observed. Cu3Si clusters were observed at structural defects within all four materials; XBIC measurements revealed that the presence of Cu3Si corresponds to increased recombination activity. Oxidized Cu compounds are not likely to form in silicon. The +1 eV edge shift in the -XAS absorption spectrum of Cu3Si relative to Cu metal is believed to be an indication of a degree of covalent bonding between Cu atoms and their silicon neighbors.
the chemical state and distribution of Cu-rich clusters were determined in four different silicon... more the chemical state and distribution of Cu-rich clusters were determined in four different silicon-based materials with varying contamination pathways and degrees of oxygen concentration, including as-grown multicrystalline silicon. In all four samples, Cu3Si was the only chemical state observed. Cu3Si clusters were observed at structural defects within all four materials; XBIC measurements revealed that the presence of Cu3Si corresponds to increased recombination activity. Oxidized Cu compounds are not likely to form in silicon. The +1 eV edge shift in the -XAS absorption spectrum of Cu3Si relative to Cu metal is believed to be an indication of a degree of covalent bonding between Cu atoms and their silicon neighbors.
X-ray fluorescence microscopy (mu-XRF), x-ray beam induced current (XBIC), and x-ray absorption s... more X-ray fluorescence microscopy (mu-XRF), x-ray beam induced current (XBIC), and x-ray absorption spectromicroscopy (mu-XAS) were performed on fully-processed Bay Six cast multicrystalline silicon and aluminum-gettered AstroPower Silicon-Film(TM) sheet material. Over ten iron precipitates--predominantly of iron silicide--were identified at low lifetime regions in both materials, both at grain boundaries and intragranular defects identified by XBIC. In addition, large (micron-sized) particles containing oxidized iron and other impurities (Ca, Cr, Mn) were found in BaySix material. The smaller iron silicide precipitates were more numerous and spatially distributed than their larger oxidized iron counterparts, and thus deemed more detrimental to minority carrier diffusion length.
ABSTRACT Synchrotron-based microprobe techniques have been applied to study the distribution, siz... more ABSTRACT Synchrotron-based microprobe techniques have been applied to study the distribution, size, chemical state, and recombination activity of Fe clusters in two types of mc-Si materials: block cast mc-Si, and AstroPower Silicon Film(TM) sheet material. In sheet material, high concentrations of metals were found at recombination-active, micron-sized intragranular clusters consisting of micron and sub-micron sized particles. In addition, Fe nanoparticles were located in densities of â2'107 cm-2 along recombination-active grain boundaries. In cast mc-Si,two types of particles were identified at grain boundaries: (1) micron-sized oxidized Fe particles accompanied by other metals (Cr, Mn, Ca, Ti), and (2) a higher number of sub-micron FeSi2 precipitates that exhibited a preferred orientation along the crystal growth direction. In both materials, it is believed that the larger Fe clusters are inclusions of foreign particles, from which Fe dissolves in the melt to form the smaller FeSi2 nanoprecipitates, which by virtue of their more homogeneous distribution are deemed more dangerous to solar cell device performance. Based on this understanding, strategies proposed to reduce the impact of Fe on mc-Si electrical properties include gettering, passivation, and limiting the dissolution of foreign Fe-rich particles in the melt.
Conference Record of the Thirty-first IEEE Photovoltaic Specialists Conference, 2005., 2005
... Tonio Buonassisi'.', Andrei A. Istratov"2, Matthew A. ... more ... Tonio Buonassisi'.', Andrei A. Istratov"2, Matthew A. Marcus'*3, Stefan Peters4; Christophe BalliPt, Matthias Heuer5, Ted F. Ciszek6, Zhonghou Cai', Bany Lai', Roland Schindler , ficke R. Webe?" Lawrence Berkeley National Laboratory, Berkeley, CA; 'Department of Materials ...
A high flux, non-destructive X-ray synchrotron-based technique, X-ray fluorescence microscopy (μ-... more A high flux, non-destructive X-ray synchrotron-based technique, X-ray fluorescence microscopy (μ-XRF), is able to detect metal precipitates as small as a few tens of nanometers in diameter within a silicon matrix, with micron-scale spatial resolution. When ...
We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, a... more We report the observation of an alloy phase with fluorite-type structure containing Ni, Fe, Cu, and Si, found as precipitates in multicrystalline silicon. The analysis of extended x-ray absorption fine-structure microspectroscopy (μ-EXAFS) measurements on the K edges of ...
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