Improvement of multicrystalline silicon solar cells by a low temperature anneal after emitter diffusion

Rinio, Markus; Yodyunyong, A.; Keipert-Colberg, Sinje; Mouafi, Yves Patrick Botchak; Borchert, D.; Montesdeoca-Santana, A.

doi:10.1002/pip.1002

Cited by 73 publications

(71 citation statements)

References 10 publications

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“…3.2.1, including a "preanneal peak" (Peak) and low-temperature anneal (Anneal), have been shown to reduce [Fe,] more effectively [26,67,[84][85][86][87]. In Michl et al, four variations of phosphorus diffusion time-temperature profile shape were analyzed.…”

Section: Different Pdg Approaches (Preanneal Peak Standard Pdg Annementioning

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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Section: Different Pdg Approaches (Preanneal Peak Standard Pdg Annementioning

confidence: 99%

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

et al. 2015

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“…[36] The 700 °C LTA enhanced the solubility segregation toward the highly doped emitter at lower temperatures and allowed the equilibrium segregation condition to be reached. [42,43] The resulting sheet resistance of the phosphorus n + layer was measured with a four-point probe to be ≈25 Ω sq −1 . The phosphorus depth profile was previously probed via secondary ion mass spectroscopy in a similarly manufactured emitter in ref.…”

Section: Methodsmentioning

confidence: 99%

Electronic Quality Improvement of Highly Defective Quasi‐Mono Silicon Material by Phosphorus Diffusion Gettering

Liu

Vähänissi

Laine

et al. 2017

Adv Elect Materials

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Quasi‐mono silicon (QM‐Si) attracts interest as a substrate material for silicon device processing with the promise to yield single‐crystalline silicon quality with multicrystalline silicon cost. A significant barrier to widespread implementation of QM‐Si is ingot edge‐contamination caused by the seed material and crucible walls during crystal growth. This work aims to recover the scrap material in QM‐Si manufacturing with a process easily adaptable to semiconductor device manufacturing. A phosphorus diffusion process at 870 °C for 60 min significantly improves the electronic quality of a QM‐Si wafer cut from a contaminated edge brick. The harmonic minority carrier recombination lifetime of the wafer, a key predictor of ultimate device performance, experiences a tenfold increase from 17 to 178 µs, which makes the scrap QM‐Si material usable for device fabrication. Local areas with suboptimal (<50 µs) lifetimes remaining can be further improved by a high temperature anneal before the phosphorus diffusion process.

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“…This step has been widely investigated and it has been highlighted that the gettering efficiency depends strongly on the as-grown iron concentration and distribution [6][7][8]. Some defect engineering tools have been developed recently based on this understanding to enhance the purification effect, such as the so-called extended gettering [9][10][11]. The phosphorus gettering efficiency using different temperature profiles has been successfully proved in solar-grade materials [12].…”

Section: Introductionmentioning

confidence: 99%

Lifetime improvement after phosphorous diffusion gettering on upgraded metallurgical grade silicon

Peral

Mı́guez²,

Ordás³

et al. 2014

Solar Energy Materials and Solar Cells

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Wide experimental evidence of the phosphorus diffusion gettering beneficial effect on solar grade silicon is found by measuring electron effective lifetime and interstitial iron concentration in as-grown and post processed samples from two ingots of upgraded metallurgical grade silicon produced by Ferrosolar. Results after two different P-diffusion processes are compared: P emitter diffusion at 850ºC followed by fast cool-down (called "standard process") or followed by slow cool-down (called "extended process"). It is shown that final lifetimes of this low cost material are in the range of those obtained with conventional material. The extended process can be beneficial for wafers with specific initial distribution and concentration of iron, e.g. materials with high concentration of big Fe precipitates, while for other cases the standard process is enough efficient. An analysis based on the comparison of measured lifetime and dissolved iron concentration with theoretical calculations helps to infer the initial iron distribution and concentration, and according to that, choose the more effective type of gettering.

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Improvement of multicrystalline silicon solar cells by a low temperature anneal after emitter diffusion

Cited by 73 publications

References 10 publications

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

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

Electronic Quality Improvement of Highly Defective Quasi‐Mono Silicon Material by Phosphorus Diffusion Gettering

Lifetime improvement after phosphorous diffusion gettering on upgraded metallurgical grade silicon

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