Defect engineering in cast mono‐like silicon: A review

Song, Lihui; Yu, Xuegong

doi:10.1002/pip.3364

Cited by 12 publications

(16 citation statements)

References 86 publications

(174 reference statements)

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“…The bottom and top parts of the ingot usually contain high concentrations of impurities due to their diffusion from the crucible walls and the segregation effect during the casting process 43 . As expected, the un‐gettered bottom wafers show an inferior performance with global i V OC below 540 mV.…”

Section: Resultssupporting

confidence: 53%

“…The dark line‐shaped patterns in the i V OC images (Figure 1A–D) are caused by crystallographic defects. EBSD measurements (see Figure A1) confirmed that those features are low angle grain boundaries, which are normally formed due to the movement and aggregation of a high density of dislocations 42,43 . The residual stress and strain around these dislocations can naturally capture other defects and impurities, and thus, make these regions highly recombination active 44 .…”

Section: Resultsmentioning

confidence: 87%

“…The residual stress and strain around these dislocations can naturally capture other defects and impurities, and thus, make these regions highly recombination active 44 . In the ingot casting thermal process, dislocations are generated at the seed joints 43,45 . They then multiply rapidly along the growth direction; therefore, substantially higher densities of crystallographic defects are observed in the wafers from the top of the ingot 42,43 …”

Section: Resultsmentioning

confidence: 99%

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Temperature sensitivity maps of silicon wafers from photoluminescence imaging: The effect of gettering and hydrogenation

Nie¹,

Chin²,

Soufiani³

et al. 2022

Progress in Photovoltaics

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The operating temperature has a critical impact on the electrical performance of solar cells. It has been shown that the temperature coefficient is not uniform across devices and often varies between different regions due to the inhomogeneous distributions of defects. In this study, temperature‐dependent photoluminescence imaging measurements are used to assess the influence of different processes such as gettering, firing and advanced hydrogenation on the temperature‐dependent electrical performance of cast‐mono silicon wafers. It is found that the height of the wafer within the ingot impacts the response of the temperature coefficient to different fabrication processes. Advanced hydrogenation is found to reduce the temperature sensitivity, more than expected solely from the improvement in implied open‐circuit voltage. Crystallographic defects are found to be the least temperature sensitive regions, indicating that their detrimental impact is reduced at higher operating temperatures. The interesting low temperature sensitivity in the defective regions is further investigated using hyperspectral photoluminescence imaging measurements and atom probe tomography. It is suggested that the reduced sensitivity is due to impurities decorating crystallographic defects.

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Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Temperature sensitivity maps of silicon wafers from photoluminescence imaging: The effect of gettering and hydrogenation

Nie¹,

Chin²,

Soufiani³

et al. 2022

Progress in Photovoltaics

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show abstract

“…Recently, a rapid developing technology, namely, cast-monosilicon (cm-Si), has taken a certain market share. [1] Due to the development of a proper seed arrangement and the use of functional grain boundary technology, the propagation of dislocations in cm-Si could be effectively suppressed, [2,3] resulting in the conversion efficiency of cm-Si passivated emitter rear contact (PERC) solar cells exceeding 23%. In addition, the growth process of cm-Si is fully compatible with that of mc-Si, which is suitable for mass production.Light-and elevated-temperature-induced degradation (LeTID) is a significant problem in PERC solar cells.…”

mentioning

confidence: 99%

Kinetics Study on Carrier Injection‐Induced Degradation and Regeneration at Elevated Temperature in p‐Type Cast‐Monosilicon Passivated Emitter Rear Contact Solar Cells

Yuan

et al. 2021

Solar RRL

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Herein, the degradation and regeneration processes of p‐type cast‐monosilicon passivated emitter rear contact solar cells are investigated, by taking open‐circuit voltage as a measure for the light‐ and elevated‐temperature‐induced degradation (LeTID) and regeneration extent. Degradation and regeneration are triggered by current injection and light soaking at the same temperatures. Then, an Arrhenius plot, derived from the proposed model, is used to extract the degradation and regeneration rate constants of LeTID during both current injection and light‐soaking processes. The activation energies of degradation processes are calculated to be (0.790 ± 0.064) and (0.828 ± 0.013) eV for current injection and light soaking, respectively. The corresponding activation energies for regeneration processes are (1.059 ± 0.112) and (1.179 ± 0.070) eV, respectively. Notably, the similar activation energies indicate that the root cause of the LeTID induced by current injection or light soaking is the same. In addition, an exponential dependence of the rate constants upon the injection current values during the whole degradation and regeneration cycle induced by current injection is observed. These results are not only significant for understanding the kinetics of LeTID but also can shed light on effective LeTID suppression method in the photovoltaic industry.

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“… 4 However, the bottom red zone because of the metal contamination and the high dislocation region at the top of the ingot are still the practical drawbacks, which limited its competitiveness to the monocrystalline Si grown by the Czochralski method. 5 Crystal structures and properties of the mono-like DS-Si ingots depend on the seed arrangement, growth interface evolution, generation and propagation of dislocations, thermal stress relaxation, impurity transport, etc. Especially, the high dislocation density gives negative influence on the conversion efficiency of solar cells by providing not only recombination sites for minority carriers but also shunt regions for majority carriers.…”

Section: Introductionmentioning

confidence: 99%

Data-Driven Optimization and Experimental Validation for the Lab-Scale Mono-Like Silicon Ingot Growth by Directional Solidification

et al. 2022

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The casting mono-like silicon (Si) grown by directional solidification (DS) is promising for high-efficiency solar cells. However, high dislocation clusters around the top region are still the practical drawbacks, which limit its competitiveness to the monocrystalline Si. To optimize the DS-Si process, we applied the framework, which integrates the growing experiments, transient global simulations, artificial neuron network (ANN) training, and genetic algorithms (GAs). First, we grew the Si ingot by the original recipe and reproduced it with transient global modeling. Second, predictions of the Si ingot domain from different recipes were used to train the ANN, which acts as the instant predictor of ingot properties from specific recipes. Finally, the GA equipped with the predictor searched for the optimal recipe according to multi-objective combination, such as the lowest residual stress and dislocation density. We also implemented the optimal recipe in our mono-like DS-Si process for verification and comparison. According to the optimal recipe, we could reduce the dislocation density and smooth the growth rate during the Si ingot growing process. Comparisons of the growth interface and grain boundary evolutions showed the decrease of the interface concavity and the multi-crystallization in the top part of the ingot. The well-trained ANN combined with the GA could derive the optimal growth parameter combinations instantly and quantitatively for the multi-objective processes.

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Defect engineering in cast mono‐like silicon: A review

Cited by 12 publications

References 86 publications

Temperature sensitivity maps of silicon wafers from photoluminescence imaging: The effect of gettering and hydrogenation

Temperature sensitivity maps of silicon wafers from photoluminescence imaging: The effect of gettering and hydrogenation

Kinetics Study on Carrier Injection‐Induced Degradation and Regeneration at Elevated Temperature in p‐Type Cast‐Monosilicon Passivated Emitter Rear Contact Solar Cells

Data-Driven Optimization and Experimental Validation for the Lab-Scale Mono-Like Silicon Ingot Growth by Directional Solidification

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