An insight into dislocation density reduction in multicrystalline silicon

Woo, Soobin; Bertoni, Mariana I.; Choi, Kwangmin; Nam, Sangwook; Castellanos, Sergio; Powell, Douglas M.; Buonassisi, Tonio; Choi, Hong‐Shik

doi:10.1016/j.solmat.2016.03.040

Cited by 32 publications

(12 citation statements)

References 152 publications

(186 reference statements)

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“…As seen above and based on the crystallographic orientation of the up-grown crystal ( Fig. 6 b and c), which is the same as the seed, and observing the line vector parallel to the [ 011 ] direction, the grown-in dislocations can either glide in the vertical ( 1 1 1 ) or the ( 11 1 ) glide plane which is almost parallel to the surface of the sample (perpendicular to our field of view). Some, clear dislocation lines move laterally below the growth front in the Bragg diffraction images ( Fig.…”

Section: Grown-in Dislocationsmentioning

confidence: 82%

Dynamic observation of dislocation evolution and interaction with twin boundaries in silicon crystal growth using in – situ synchrotron X-ray diffraction imaging

et al. 2021

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The grown-in dislocation dynamics and interaction mechanisms with growth twins are investigated in-situ during the directional solidification of silicon crystal. The melting, solidification and cooling down process is performed in a dedicated installation at the European synchrotron radiation facility and is fol-lowed by X-ray Bragg diffraction imaging techniques (X-ray topography) at the mesoscale in real-time. Existing dislocations in the seed are observed to propagate in the up-grown crystal via replicas. They ex-pand vertically with the moving solid-liquid interface being always aligned perpendicular to the growth front. During the solidification process when they meet a growth twin lamella ( 3{111}), they neither pile-up nor transmit through the boundary. They are blocked by the twin, but they continue to move laterally behind the growth front due to the thermomechanical stresses in the system. The existence of dis-locations at the solidliquid interface, their evolution and interaction with twin boundaries is discussed, as growth proceeds, based on a detailed crystallographic analysis of the system.

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Section: Grown-in Dislocationsmentioning

confidence: 82%

Dynamic observation of dislocation evolution and interaction with twin boundaries in silicon crystal growth using in – situ synchrotron X-ray diffraction imaging

et al. 2021

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“…Indeed, dislocations play a major role on the efficiency of solar cells, because they can act as preferential segregation sites for impurities, ultimately reducing the carrier lifetime [2][3][4]. As such, dislocations remain one of the most important efficiency limiting defects in Si for PV applications [5,6] for which defect engineering is needed [7]. At a higher scale, subgrain boundaries and grain boundaries of high planar mismatch can be more detrimental than high symmetry grain boundaries such as symmetric coincidence site lattice (CSL) twin boundaries, also due to decoration by impurities [8].…”

Section: Introductionmentioning

confidence: 99%

Strain building and correlation with grain nucleation during silicon growth

et al. 2019

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This work is dedicated to the grain structure formation in silicon ingots with a particular focus on the crystal structure strain building and its implication in new grain nucleation process. The implied mechanisms are investigated by advanced in situ X-ray imaging techniques during silicon directional solidification. It is shown that the grain structure formation is mainly driven by Σ3 <111> twin nucleation. Grain competition phenomena occurring during the growth process lead to the creation of higher order twin boundaries, localised strained areas and associated crystal structure deformation. On the one hand, it is demonstrated that local strain building can be directly related to the characteristics of the twin boundaries created during silicon growth due to grain competition. On the other hand, space restriction due to competition during growth can be at the origin of local strain building as well. Finally, the accumulation of all these factors generating strain is responsible for spontaneous new grain nucleation. When occurring, both grain nucleation and subsequent grain structure reorganisation contribute to lower the strain in the growing ingot.It is demonstrated as well that the local distribution of the strained areas created during silicon growth is retrieved after cooling down, from melting temperature to room temperature, on top of an additional larger scale deformation of the sample due to the cooling down only.

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“…In the field of silicon research for photovoltaic (PV) applications, real-time characterization of the solidification process is crucial to understand the critical mechanisms producing defects during growth. Some types of defects can severely limit the conversion efficiency of solar cells by reducing the minority-carrier lifetime (Oliveira et al, 2016;Woo et al, 2016;Wang et al, 1999;Fedotov et al, 1990). One of the most widely used silicon ingot fabrication methods for solar cells is directional solidification.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous X-ray radiography and diffraction topography imaging applied to silicon for defect analysis during melting and crystallization

Becker¹,

Regula²,

Reinhart³

et al. 2019

J Appl Cryst

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One of the key issues to be resolved to improve the performance of silicon solar cells is to reduce crystalline defect formation and propagation during the growth‐process fabrication step. For this purpose, the generation of structural defects such as grain boundaries and dislocations in silicon must be understood and characterized. Here, in situ X‐ray diffraction imaging, historically named topography, is combined with radiography imaging to analyse the development of crystal defects before, during and after crystallization. Two individual indirect detector systems are implemented to record simultaneously the crystal structure (topographs) and the solid–liquid morphology evolution (radiographs) at high temperature. This allows for a complete synchronization of the images and for an increased image acquisition rate compared with previous studies that used X‐ray sensitive films to record the topographs. The experiments are performed with X‐ray synchrotron radiation at beamline ID19 at the European Synchrotron Radiation Facility. In situ observations of the heating, melting, solidification and holding stages of silicon samples are presented, to demonstrate that with the upgraded setup detailed investigations of time‐dependent phenomena are now possible. The motion of dislocations is recorded throughout the experiment, so that their interaction with grain boundaries and their multiplication through the activation of Frank–Read sources can be observed. Moreover, the capability to record with two camera‐based detectors allows for the study of the relationship between strain distribution, twinning and nucleation events. In conclusion, the simultaneous recording of topographs and radiographs has great potential for further detailed investigations of the interaction and generation of grains and defects that influence the growth process and the final crystalline structure in silicon and other crystalline materials.

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An insight into dislocation density reduction in multicrystalline silicon

Cited by 32 publications

References 152 publications

Dynamic observation of dislocation evolution and interaction with twin boundaries in silicon crystal growth using in – situ synchrotron X-ray diffraction imaging

Dynamic observation of dislocation evolution and interaction with twin boundaries in silicon crystal growth using in – situ synchrotron X-ray diffraction imaging

Strain building and correlation with grain nucleation during silicon growth

Simultaneous X-ray radiography and diffraction topography imaging applied to silicon for defect analysis during melting and crystallization

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