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Hans Siethoff - One of the best experts on this subject based on the ideXlab platform.
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The interaction of boron and phosphorus with dislocations in silicon
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: Hans Siethoff, H. G. BrionAbstract:We present measurements of the Lower Yield Point of highly boron doped silicon. Comparison to similar investigations on phosphorus doped material reveals a principally different temperature dependence of the Lower Yield stress, although the doping concentration of the crystals and the strain-rate and temperature ranges of the experiments were the same. In boron doped silicon, a temperature independent domain emerges, while for phosphorus doping there remains a well-defined temperature dependence. Apparently the interaction of boron with dislocations in silicon is different from that of phosphorus. Suitable models are available to describe the different influence of both dopants on the Yield Point.
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The deformation regimes of the Yield Point of silicon
Philosophical Magazine A, 2001Co-Authors: Hans Siethoff, H. G. BrionAbstract:The upper Yield Point of undoped floating-zone silicon has been investigated. The measurements were performed on dislocation-free single crystals deformed at temperatures between 800 and 1300°C and a strain-rate range extending over three orders of magnitude. The upper Yield Point emerges up to 1250°C. In principle, the data reflect the behaviour of the Lower Yield Point, thus confirming the existence of a novel deformation regime of silicon at high temperatures and small strain rates. There are, however, features which resemble the behaviour of highly doped material to some extent. This surprising similarity raises questions concerning the interpretation of the different deformation regimes observed in undoped and doped silicon.
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A regime of the Yield Point of silicon at high temperatures
Applied Physics Letters, 1999Co-Authors: Hans Siethoff, H. G. Brion, Wolfgang SchröterAbstract:We present measurements of the Lower Yield Point of undoped floating-zone silicon at temperatures between 800 and 1300 °C. The knowledge of the defect structure in this temperature range is of considerable importance for the numerical simulation of dislocation generation in various solar silicon materials. Above about 1050 °C, we find marked deviations from the well-known low-temperature behavior, thus establishing a further deformation regime. It is characterized by an activation energy of 4.1 eV. Comparison to preliminary work indicates that this effect depends on the as-grown dislocation density, but not on the ambient during deformation. We tentatively assume that it may reflect the change in the mechanism of self-diffusion typical for silicon at high temperatures.
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Dynamical recovery, dislocation mobility, and diffusion in undoped semiconductors
Physica Status Solidi (a), 1993Co-Authors: Hans SiethoffAbstract:Two characteristic stages of the stress-strain curve of undoped elemental and compound semiconductors are correlated: the Lower Yield Point and the first stage of dynamical recovery (stage III). While the former is assumed to be governed by the stress and temperature dependence of the dislocation mobility, the latter has been shown to be dominated by diffusion-controlled climb. Both mechanisms are thermally activated with a well-defined activation energy. The correlation manifests itself in the fact that the ratio of these activation energies is practically the same for all semiconductors investigated so far. This, eventually, indicates that a diffusional step is probably involved in the elementary process underlying the dislocation motion. Zwei charakteristische Bereiche der Verfestigungskurve von undotierten Element- und Verbindungs-halbleitern sind korreliert: die untere Streckgrenze und die erste Stufe der dynamischen Erholung (Bereich III). Man nimmt an, das die Streckgrenze durch die Spannungs- und Temperaturabhangig-keit der Versetzungsbewegung, Bereich III hingegen durch diffusionskontrolliertes Klettern bestimmt ist. Beide Mechanismen sind thermisch aktiviert und besitzen eine wohldefinierte Aktivierungsenergie. Die Korrelation zeigt sich in der Tatsache, das das Verhaltnis dieser Aktivierungsenergien fur alle bisher untersuchten Halbleiter praktisch gleich ist. Dies bedeutet, das wahrscheinlich ein elementarer Diffusionsschritt in den Grundprozes der Versetzungsbewegung mit einbezogen ist.
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plastic deformation of gasb and the influence of stacking fault energy on dynamical recovery of semiconductors
Physica Status Solidi (a), 1991Co-Authors: Hans Siethoff, H. G. Brion, W. SchröterAbstract:Undoped GaSb single crystals with 〈123〉 orientation are compressed at different strain rates in the temperature range between 430 and 570°C. The resulting stress strain curves arc rather similar to those observed for other semiconductors. From the Lower Yield Point, an activation energy U = 1.2 eV and a stress exponent m = 1 (of the dislocation mobility) are deduced. The analysis of the first stage of dynamical recovery (deformation stage III) Yields an activation energy QD = 1.7 eV and a stress exponent n = 3.8. The ratio QD/U = 1.42 is of the same magnitude as that found for other semiconductors. The first recovery stage is interpreted in terms of diffusion-controlled climb; special aspects of diffusion in III-V compounds are discussed. Comparison of the different elemental and compound semiconductors investigated so far establishes a quantitative relation between stacking-fault energy and the stress exponent of the first recovery stage; GaAs, however, is an exception to this rule. Undotierte, nach 〈123〉 orientierte Einkristalle von GaSb werden bei verschiedenen Dehngeschwindigkciten und Temperaturen zwischen 430 und 570°C im Druckversuch verformt. Die resultierenden Verfestigungskurven sind denen anderer Halbleiter sehr ahnlich. Die untere Streckgrenze ist durch eine Aktivierungsenergie U = 1.2 eV und einen Spannungsexponenten m = 1 (der Versetzungsbeweglichkeit) gekennzeichnet. Die Analyse der ersten Stufe der dynamischen Erholung (Verformungsbereich III) ergibt eine Aktivierungsenergie QD = 1,7 eV und einen Spannungsexponenten n = 3,8. Das Verhaltnis QD/U = 1,42 ist von gleicher Grose wie bei anderen Halbleitern. Die erste Erholungsstufe wird mit diffusionskontrolliertem Klettern erklart, wobei die besonderen Aspekte der Diffusion in III-V Verbindungen berucksichtigt werden. Ein Vergleich der bisher untersuchtcn Element- und Verbindungsbhalbleiter fuhrt auf eine quantitative Beziehung zwischen Stapelfehlerenergie und dem Spannungsexponenten der ersten Erholungsstufe, von der GaAs jedoch ausgenommen ist.
H. G. Brion - One of the best experts on this subject based on the ideXlab platform.
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The interaction of boron and phosphorus with dislocations in silicon
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003Co-Authors: Hans Siethoff, H. G. BrionAbstract:We present measurements of the Lower Yield Point of highly boron doped silicon. Comparison to similar investigations on phosphorus doped material reveals a principally different temperature dependence of the Lower Yield stress, although the doping concentration of the crystals and the strain-rate and temperature ranges of the experiments were the same. In boron doped silicon, a temperature independent domain emerges, while for phosphorus doping there remains a well-defined temperature dependence. Apparently the interaction of boron with dislocations in silicon is different from that of phosphorus. Suitable models are available to describe the different influence of both dopants on the Yield Point.
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The deformation regimes of the Yield Point of silicon
Philosophical Magazine A, 2001Co-Authors: Hans Siethoff, H. G. BrionAbstract:The upper Yield Point of undoped floating-zone silicon has been investigated. The measurements were performed on dislocation-free single crystals deformed at temperatures between 800 and 1300°C and a strain-rate range extending over three orders of magnitude. The upper Yield Point emerges up to 1250°C. In principle, the data reflect the behaviour of the Lower Yield Point, thus confirming the existence of a novel deformation regime of silicon at high temperatures and small strain rates. There are, however, features which resemble the behaviour of highly doped material to some extent. This surprising similarity raises questions concerning the interpretation of the different deformation regimes observed in undoped and doped silicon.
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A regime of the Yield Point of silicon at high temperatures
Applied Physics Letters, 1999Co-Authors: Hans Siethoff, H. G. Brion, Wolfgang SchröterAbstract:We present measurements of the Lower Yield Point of undoped floating-zone silicon at temperatures between 800 and 1300 °C. The knowledge of the defect structure in this temperature range is of considerable importance for the numerical simulation of dislocation generation in various solar silicon materials. Above about 1050 °C, we find marked deviations from the well-known low-temperature behavior, thus establishing a further deformation regime. It is characterized by an activation energy of 4.1 eV. Comparison to preliminary work indicates that this effect depends on the as-grown dislocation density, but not on the ambient during deformation. We tentatively assume that it may reflect the change in the mechanism of self-diffusion typical for silicon at high temperatures.
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Dynamical Recovery of In-Doped 〈123〉 GaAs†
Physica Status Solidi (a), 1993Co-Authors: H. G. Brion, K. Ahlborn, H. SiethoffAbstract:GaAs 〈123〉 single crystals, doped with 5 × 1019 In/cm3, are deformed in compression at different strain rates in the temperature range between 550 and 900 °C. The shape of the resulting stress-strain curves is rather similar to that found for other undoped and doped semiconductors: beyond the Yield Point, at low temperatures three and at high temperatures five deformation stages are observed. At 900 °C and low strain rates an additional structure emerges in stage I which, probably, is caused by the Portevin-LeChatelier effect appearing at these conditions. The first stage of dynamical recovery (represented by the stress τIII) exhibits a complicated behavior. In the regime occurring at temperatures between 730 and 900 °C, the strain-rate and temperature dependence of τIII, is characterized by a power law and an Arrhenius law, respectively. The resulting parameters, however, are not compatible with a diffusion-controlled climb mechanism; they are rather explained by thermally-activated glide of dislocations past obstacles, as it was formerly done for highly doped Si and Ge. At temperatures between 550 and 660 °C, a different regime with a weaker strain-rate and temperature dependence is observed, the origin of which is not clear at the moment. At 900 °C (and low strain rates), finally, a stress plateau emerges, which is probably caused by the Portevin-LeChatelier effect, but which does not behave as stress plateaus sometimes found in the strain-rate dependence of the Lower Yield Point of heavily doped semiconductors. Einkristalle von 〈123〉 GaAs, die mit 5 × 1019 In/cm3 dotiert sind, werden bei verschiedenen Dehnungs-geschwindigkeiten und Temperaturen zwischen 550 und 900 °C in Kompression verformt. Die resultierenden Verfestigungskurven sind hinsichtlich ihrer Form denen anderer undotierter und dotierter Halbleiter sehr ahnlich: nach der Streckgrenze werden bei tiefen Temperaturen drei und bei hohen Temperaturen funf Verformungsstufen beobachtet. Bei 900 °C und kleinen Dehnungsraten entsteht im Verformungsbereich I eine weitere Struktur, die wahrscheinlich durch den bei diesen Bedingungen auftretenden Portevin-LeChatelier-Effekt hervorgerufen wird. Die erste Stufe der dynamischen Erholung (reprasentiert durch die Spannung τIII) weist ein kompliziertes Verhalten auf. Der bei Temperaturen zwischen 730 und 900 °C auftretende Bereich zeigt eine Abhangigkeit dieser Spannung von Dehnungsrate und Temperatur, die durch ein Potenz- bzw. durch ein Arrheniusgesetz gekennzeichnet ist. Die resultierenden Parameter sind jedoch nicht mit einem diffusionskontrollierten Klettermechanismus vertraglich, sondern werden — wie schon fruher bei hochdotiertem Si und Ge — mit thermisch aktivierter Gleitung von Versetzungen uber Hindernisse erklart. Bei Temperaturen zwischen 550 und 660 °C wird ein Bereich mit einer schwacheren Abhangigkeit von Temperatur und Dehnungsrate beobachtet, dessen Deutung aber noch nicht klar ist. Bei 900 °C (und kleinen Dehnungsraten) bildet sich ein Spannungsplateau heraus, das wahrscheinlich durch den Portevin-LeChatelier-Effekt verursacht wird, das sich aber nicht wie die Spannungsplateaus verhalt, die gelegentlich in der Geschwindigkeitsabhangigkeit der unteren Streckgrenze von hochdotierten Halbleitern auftreten.
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plastic deformation of gasb and the influence of stacking fault energy on dynamical recovery of semiconductors
Physica Status Solidi (a), 1991Co-Authors: Hans Siethoff, H. G. Brion, W. SchröterAbstract:Undoped GaSb single crystals with 〈123〉 orientation are compressed at different strain rates in the temperature range between 430 and 570°C. The resulting stress strain curves arc rather similar to those observed for other semiconductors. From the Lower Yield Point, an activation energy U = 1.2 eV and a stress exponent m = 1 (of the dislocation mobility) are deduced. The analysis of the first stage of dynamical recovery (deformation stage III) Yields an activation energy QD = 1.7 eV and a stress exponent n = 3.8. The ratio QD/U = 1.42 is of the same magnitude as that found for other semiconductors. The first recovery stage is interpreted in terms of diffusion-controlled climb; special aspects of diffusion in III-V compounds are discussed. Comparison of the different elemental and compound semiconductors investigated so far establishes a quantitative relation between stacking-fault energy and the stress exponent of the first recovery stage; GaAs, however, is an exception to this rule. Undotierte, nach 〈123〉 orientierte Einkristalle von GaSb werden bei verschiedenen Dehngeschwindigkciten und Temperaturen zwischen 430 und 570°C im Druckversuch verformt. Die resultierenden Verfestigungskurven sind denen anderer Halbleiter sehr ahnlich. Die untere Streckgrenze ist durch eine Aktivierungsenergie U = 1.2 eV und einen Spannungsexponenten m = 1 (der Versetzungsbeweglichkeit) gekennzeichnet. Die Analyse der ersten Stufe der dynamischen Erholung (Verformungsbereich III) ergibt eine Aktivierungsenergie QD = 1,7 eV und einen Spannungsexponenten n = 3,8. Das Verhaltnis QD/U = 1,42 ist von gleicher Grose wie bei anderen Halbleitern. Die erste Erholungsstufe wird mit diffusionskontrolliertem Klettern erklart, wobei die besonderen Aspekte der Diffusion in III-V Verbindungen berucksichtigt werden. Ein Vergleich der bisher untersuchtcn Element- und Verbindungsbhalbleiter fuhrt auf eine quantitative Beziehung zwischen Stapelfehlerenergie und dem Spannungsexponenten der ersten Erholungsstufe, von der GaAs jedoch ausgenommen ist.
Wolfgang Schröter - One of the best experts on this subject based on the ideXlab platform.
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A regime of the Yield Point of silicon at high temperatures
Applied Physics Letters, 1999Co-Authors: Hans Siethoff, H. G. Brion, Wolfgang SchröterAbstract:We present measurements of the Lower Yield Point of undoped floating-zone silicon at temperatures between 800 and 1300 °C. The knowledge of the defect structure in this temperature range is of considerable importance for the numerical simulation of dislocation generation in various solar silicon materials. Above about 1050 °C, we find marked deviations from the well-known low-temperature behavior, thus establishing a further deformation regime. It is characterized by an activation energy of 4.1 eV. Comparison to preliminary work indicates that this effect depends on the as-grown dislocation density, but not on the ambient during deformation. We tentatively assume that it may reflect the change in the mechanism of self-diffusion typical for silicon at high temperatures.
Chung-yun Kang - One of the best experts on this subject based on the ideXlab platform.
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Effect of Ni content on the tensile properties and strain-induced martensite transformation for 304 stainless steel
Materials Science and Engineering: A, 2011Co-Authors: Do-yeal Ryoo, Namhyun Kang, Chung-yun KangAbstract:Abstract The effect of Ni content (8.3–12 wt.%) on the tensile properties and strain hardening behavior was studied on type 304 stainless steels (STS) used for the membrane of LNG storage tanks. The tensile test temperature was varied from 25 °C to −196 °C. At room temperature, the hardening and ductility indices (tensile strength, strain hardening exponent and elongation) increased with decreasing Ni content. For the 8.3–9.0 wt.% Ni STS, a Lower Yield Point was observed at temperatures below −60 °C. It was due to the dynamic strain softening and/or transformation-induced plasticity (TRIP) that accompanied the rapid increase in the amount of strain-induced martensite (α′) at low strains. Neither dynamic strain softening nor TRIP was observed for the 12 wt.% Ni STS because only the ɛ-martensite transformation was produced at the low strains.
Do-yeal Ryoo - One of the best experts on this subject based on the ideXlab platform.
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Effect of Ni content on the tensile properties and strain-induced martensite transformation for 304 stainless steel
Materials Science and Engineering: A, 2011Co-Authors: Do-yeal Ryoo, Namhyun Kang, Chung-yun KangAbstract:Abstract The effect of Ni content (8.3–12 wt.%) on the tensile properties and strain hardening behavior was studied on type 304 stainless steels (STS) used for the membrane of LNG storage tanks. The tensile test temperature was varied from 25 °C to −196 °C. At room temperature, the hardening and ductility indices (tensile strength, strain hardening exponent and elongation) increased with decreasing Ni content. For the 8.3–9.0 wt.% Ni STS, a Lower Yield Point was observed at temperatures below −60 °C. It was due to the dynamic strain softening and/or transformation-induced plasticity (TRIP) that accompanied the rapid increase in the amount of strain-induced martensite (α′) at low strains. Neither dynamic strain softening nor TRIP was observed for the 12 wt.% Ni STS because only the ɛ-martensite transformation was produced at the low strains.
