Improved multicrystalline silicon ingot crystal quality through seed growth for high efficiency solar cells

Jouini, Ahlem; Ponthenier, D.; Lignier, Hélène; Enjalbert, N.; Marie, B.; Drevet, B.; Pihan, É.; Cayron, Cyril; Lafford, Tamzin; Camel, D.

doi:10.1002/pip.1221

Cited by 74 publications

(47 citation statements)

References 8 publications

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“…Two approaches have been reported in the literature, which represent the two extreme grain configurations; the ML-Si and the HP mc-Si. On the one hand, in the case of ML-Si, a pavement of monocrystalline seeds is placed on the bottom of the crucible in order to grow a mono-crystalline ingot, taking up the initial orientation of the seed [4]. However, ML-Si efficiencies are still limited due to the presence of structural defects such as parasitic grain nucleation on the walls of the crucible [5,6], twin formation and dislocations.…”

Section: Introductionmentioning

confidence: 98%

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: 98%

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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“…The first 2D Model consists of heterogeneously distributed dislocations and no grain boundaries, representing mono-like [52][53][54][55][56][57][58][59] and epitaxial silicon [60][61][62][63]. The second 2D Model adds a grain boundary to the dislocations, simulating conventional multicrystalline silicon (mc-Si).…”

Section: B3smentioning

confidence: 99%

Building intuition of iron evolution during solar cell processing through analysis of different process models

et al. 2015

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An important aspect of Process Simulators for photovoltaics is prediction of defect evolution during device fabrication. Over the last twenty years, these tools have accelerated process optimization, and several Process Simulators for iron, a ubiquitous and deleterious impurity in silicon, have been developed. The diversity of these tools can make it difficult to build intuition about the physics governing iron behavior during processing. Thus, in one unified software environment and using self-consistent terminology, we combine and describe three of these Simulators. We vary structural defect distribution and iron precipitation equations to create eight distinct Models, which we then use to simulate different stages of processing. We find that the structural defect distribution influences the final interstitial iron concentration ([Fe,]) more strongly than the iron precipitation equations. We identify two regimes of iron behavior: (1) diffusivity-limited, in which iron evolution is kinetic ally limited and bulk [Fe,] predictions can vary by an order of magnitude or more, and (2) solubility-limited, in which iron evolution is near thermodynamic equilibrium and the Models yield similar results. This rigorous analysis provides new intuition that can inform Process Simulation, material, and process development, and it enables scientists and engineers to choose an appropriate level of Model complexity based on wafer type and quality, processing conditions, and available computation time.

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“…However, undesirable defects such as sub-grain boundaries and dislocations can occur, at the seed/solidified silicon interface and preferentially at the junctions of the seeds, and extend to the whole ingot during the growth process, having a serious impact on the final solar cell efficiency [4][5][6][7][8][9]. Some research has already been performed aiming to investigate the origin of these kinds of defects.…”

Section: Introductionmentioning

confidence: 99%

Mono-like silicon ingots grown on low angle misoriented seeds: Defect characterization by synchrotron X-ray diffraction imaging

et al. 2015

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Improved multicrystalline silicon ingot crystal quality through seed growth for high efficiency solar cells

Cited by 74 publications

References 8 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

Building intuition of iron evolution during solar cell processing through analysis of different process models

Mono-like silicon ingots grown on low angle misoriented seeds: Defect characterization by synchrotron X-ray diffraction imaging

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