Development of grain structures of multi-crystalline silicon from randomly orientated seeds in directional solidification

Wong, Yu-Tai; Hsu, Chuck; Lan, C.W.

doi:10.1016/j.jcrysgro.2013.10.021

Cited by 47 publications

(20 citation statements)

References 16 publications

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“…This would result in low density of dislocation clusters thanks to the interaction of blocking mechanisms by which dislocations that nucleate at the beginning of the crystallization process cannot propagate further along the growth of the ingot. In the literature, chips [15] (small Si pieces) and granules [16,17] (small spherical Si beads) have been reported to be used as seeds for HP mc-Si ingot growth with promising results. However, from the work presented on the literature, we can conclude that it is essential to better understand and control the initial grain size and orientation distribution at both bottom and walls of the crucible, as well as the initial defect density to obtain the targeted dislocation density reduction higher in the ingot [18].…”

Section: Introductionmentioning

confidence: 99%

In situ investigation of the structural defect generation and evolution during the directional solidification of 〈110〉 seeded growth Si

et al. 2016

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a b s t r a c tThis work is dedicated to the advanced in situ X-ray imaging and complementary ex situ investigations of the growth mechanisms when silicon solidifies on a monocrystalline seed oriented 〈110〉 in the solidification direction. It aims at deepening the fundamental understanding of the phenomena that occur throughout silicon crystal growth with a particular focus on mechanisms of formation of defects detrimental for photovoltaic applications. Namely, grain nucleation, grain boundary formation and evolution, grain competition, twining occurrence, dislocation generation and interaction with structural defects are explored and analysed. Nucleation of twin crystals preferentially occurs on {111} facets at the edge of the sample where solid e liquid e vapor triple point lines exist in interaction also with the crucible as well as, at grain boundary grooves at the solid e liquid interface (solid e solid e liquid triple lines), where two grains are in competition, either on the {111} facets of the groove or in the groove. Enhanced undercooling and/or stress accumulation levels are found to act as driving forces for grain nucleation. Additionally, it is demonstrated that twin formation has the property to relax stresses stored in the crystal during the growth process. However, grains formed initially in twin position can undergo severe distortion when they are in direct competition or when they are squeezed in e between grains. Moreover, we show by X-ray Bragg diffraction imaging that on the one hand, coherent S3 〈111〉 grain boundaries efficiently block the propagation of growth dislocations during the solidification process, while on the other hand, dislocations are emitted at the level of incoherent and/or asymmetric S27a 〈110〉 at the encounter with either S3 〈111〉 or S9 〈110〉 grain boundaries. Indeed, grain boundaries that deviate from the ideal coincidence orientation act as dislocation sources that spread inside the surrounding crystals.

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Section: Introductionmentioning

confidence: 99%

In situ investigation of the structural defect generation and evolution during the directional solidification of 〈110〉 seeded growth Si

et al. 2016

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“…have been previously studied in cast multi-crystalline silicon ingots by Electron Backscattered Diffraction (EBSD) [15,16]. In particular, the importance of twinning in the development of the grain structure has been highlighted for different solidification processes ranging from directional solidification [17] to ribbon growth [18].…”

Section: Introductionmentioning

confidence: 99%

On the impact of twinning on the formation of the grain structure of multi-crystalline silicon for photovoltaic applications during directional solidification

Riberi-Béridot

Mangelinck‐Noël

Tandjaoui

et al. 2015

Journal of Crystal Growth

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International audienceGrain orientation and competition during growth has been analyzed in directionally solidified multi-crystalline silicon samples. In situ and real-time characterization of the evolution of the grain structure during growth has been performed using synchrotron X-ray imaging techniques (radiography and topography). In addition, Electron Backscattered Diffraction has been used to reveal the crystalline orientations of the grains and the twin relationships. New grains formed during growth have two main origins: random nucleation and twinning. It is demonstrated that the solidified samples are dominated by ∑3 twin boundaries showing that twinning on {111} facets is the dominant phenomenon. Moreover, thanks to the in situ characterization of the growth, it is shown that twins nucleate on {111} facets located at the sides of the sample and at grain boundary grooves. The occurrence of multiple ∑3 twins during growth prevents the initial grains from developing all along the sample, and twin boundaries with higher order coincidence site lattices can form at the encounter of two grains in twin position. The grain competition phenomenon following nucleation and twinning acts as a grain selection mechanism leading to the final grain structure

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“…To further explain the more realistic situation of the three-grain tri-junctions (3GTJ) on the interface during ingot growth, Jain et al [14], further developed a three-dimensional model, referred as Jain's model. With the 3GTJ model, the twinning from certain grains during mc-Si growth experiments [15] was correctly predicted. More importantly, the required undercooling for twining was in the order of 0.3 K, which was consistent with the measured value [2,13].…”

Section: Introductionmentioning

confidence: 88%

Heterogeneous twinning during directional solidification of multi-crystalline silicon

Jhang

Regula

Reinhart

et al. 2019

Journal of Crystal Growth

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Heterogeneous twinning nucleation from the wall or gas interface during directional solidification of silicon have been modelled, and further used to clarify the details of twining observed in situ in X-ray synchrotron imaging experiments [1]. It is found that the heterogeneous twinning from the wall/grains or wall/gas/grain trijunctions requires much lower undercoolings leading to much higher twinning probability. The lower attachment energy and the contact area are the key factors for the heterogeneous nucleation of twins.

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Development of grain structures of multi-crystalline silicon from randomly orientated seeds in directional solidification

Cited by 47 publications

References 16 publications

In situ investigation of the structural defect generation and evolution during the directional solidification of 〈110〉 seeded growth Si

In situ investigation of the structural defect generation and evolution during the directional solidification of 〈110〉 seeded growth Si

On the impact of twinning on the formation of the grain structure of multi-crystalline silicon for photovoltaic applications during directional solidification

Heterogeneous twinning during directional solidification of multi-crystalline silicon

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