Control of metal impurities in “dirty” multicrystalline silicon for solar cells

Istratov, A. A.; Buonassisi, Tonio; Pickett, Matthew D.; Heuer, M.; Weber, E. R.

doi:10.1016/j.mseb.2006.06.023

Cited by 134 publications

(61 citation statements)

References 38 publications

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“…The EDS measurements showed that the copperrich phase of this sample has a composition of Cu 0.733͑4͒ Ni 0.017͑1͒ Si 0.202͑1͒ Ge 0.049͑1͒ , which could be a Nibearing Cu 3 Si with some Ge from the Si 1−x Ge x / Si layer. The composition of the Ni-Cu-silicide forming the other part of the precipitate can be given by Ni 0.309͑1͒ Cu 0.029͑1͒ Ge 0.079͑1͒ Si 0.578͑1͒ , which is close to NiSi 2 .…”

Section: A Investigations On Si 1−x Ge X / Si Samplesmentioning

confidence: 90%

“…Therefore, the PV industry is considering the possibility of using cheaper and dirtier materials. These materials are known as solar-grade silicon ͑SoG-Si͒, 2,3 and have a relatively high transition metal content, which is considered a major culprit for losses in solar cell efficiencies. 4,5 Since the majority of conventional solar cell technologies are poorly suited for solar-grade silicon, and the idea of using dirtier silicon for PV attracted renewed attention, one of the central problems that remains to be solved is the development of an effective defect engineering process for lower-purity mc-Si.…”

Section: Introductionmentioning

confidence: 99%

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Transition metal interaction and Ni-Fe-Cu-Si phases in silicon

Heuer

Buonassisi

Istratov

et al. 2007

Journal of Applied Physics

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In the present article we characterize several intermetallic phases of the Cu-Ni-Fe-Si system found as precipitates in the misfit dislocation layer of intentionally contaminated and slowly cooled Si1-x Gex Si -heterostructures. The clusters showed a characteristic phase speciation into a Cu-rich part similar to Cu3 Si and an Fe-Ni-Cu-Si phase similar to NiSi2. It is suggested that the precipitate formation of the investigated intermetallic silicides involves a homogeneous precursor phase at higher temperatures that later decomposes into the observed phases. Our results indicate that chemical reactions between metals and silicon during precipitation may reduce the lattice mismatch compared to single-metal precipitates, rendering mixed-metal-silicide precipitates more stable and energetically favorable

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Section: A Investigations On Si 1−x Ge X / Si Samplesmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Transition metal interaction and Ni-Fe-Cu-Si phases in silicon

Heuer

Buonassisi

Istratov

et al. 2007

Journal of Applied Physics

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“…For decades, 3d-transition metals in Si have been in the focus of silicon research due to their unwanted presence as contaminants [1][2][3][4][5] . Depending on the complexes that the transition metals (TMs) form, and thus on their lattice sites, deep levels can be created, forming recombination centers and, therefore, acting as lifetime killers for minority carriers 2,5 .…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the complexes that the transition metals (TMs) form, and thus on their lattice sites, deep levels can be created, forming recombination centers and, therefore, acting as lifetime killers for minority carriers 2,5 . The electric passivation of TMs is required to prevent, e.g., the malfunctioning of electronic circuits based on silicon or the efficiency degradation of solar cells.…”

Section: Introductionmentioning

confidence: 99%

Influence of n+ and p+ doping on the lattice sites of implanted Fe in Si

Silva

Wahl

Correia

et al. 2013

Journal of Applied Physics

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We report on the lattice location of implanted 59 Fe in n + -and p + -type Si by means of emission channeling. We found clear evidence that the preferred lattice location of Fe changes with the doping of the material. While in n + -type Si Fe prefers displaced bond-centered (BC) sites for annealing temperatures up to 600 • C, changing to ideal substitutional sites above 700 • C, in p + -type Si Fe prefers to be in displaced tetrahedral interstitial positions after all annealing steps. The dominant lattice sites of Fe in n + -type Si therefore seem to be well characterized for all annealing temperatures by the incorporation of Fe into vacancy-related complexes, either into single vacancies which leads to Fe on ideal substitutional sites, or multiple vacancies, which leads to its incorporation near BC sites. In contrast, in p + -type Si the major fraction of Fe is clearly interstitial (near-T or ideal T) for all annealing temperatures. The formation and possible lattice sites of Fe in FeB pairs in p + -Si are discussed. We also address the relevance of our findings for the understanding of the gettering effects caused by radiation damage or P-diffusion, the latter involving n + -doped regions.

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“…It is obvious that there is an valuable knowledge base within the microelectronics (development of ultraclean surface processes) to be taken advantage off, although it must be realized that eventually the allowable surface contamination level at a cleaned surface will be lower for crystalline Si solar cells with efficiency potential >21% than for a typical clean in advanced CMOS-processing. For the latter a lower level metallic contamination of 10 10 cm −2 is acceptable but for crystalline Si solar cells metal contamination levels of 10 9 cm −2 might be required [5]. This is a serious challenge in terms of cost-effectiveness of the cleaning and drying process as well as on the level of characterization of such low levels of metallic contaminants on non-mirror polished or even textured Si-surfaces.…”

Section: Pre-passivation Cleaningmentioning

confidence: 99%

Evolutionary process development towards next generation crystalline silicon solar cells : a semiconductor process toolbox application

et al. 2012

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Bulk crystalline Silicon solar cells are covering more than 85% of the world's roof top module installation in 2010. With a growth rate of over 30% in the last 10 years this technology remains the working horse of solar cell industry. The full Aluminum back-side field (Al BSF) technology has been developed in the 90's and provides a production learning curve on module price of constant 20% in average. The main reason for the decrease of module prices with increasing production capacity is due to the effect of up scaling industrial production. For further decreasing of the price per wattpeak silicon consumption has to be reduced and efficiency has to be improved. In this paper we describe a successive efficiency improving process development starting from the existing full Al BSF cell concept. We propose an evolutionary development includes all parts of the solar cell process: optical enhancement (texturing, polishing, antireflection coating), junction formation and contacting. Novel processes are benchmarked on industrial like baseline flows using high-efficiency cell concepts like i-PERC (Passivated Emitter and Rear Cell). While the full Al BSF crystalline silicon solar cell technology provides efficiencies of up to 18% (on cz-Si) in production, we are achieving up to 19.4% conversion efficiency for industrial fabricated, large area solar cells with copper based front side metallization and local Al BSF applying the semiconductor toolbox.

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Control of metal impurities in “dirty” multicrystalline silicon for solar cells

Cited by 134 publications

References 38 publications

Transition metal interaction and Ni-Fe-Cu-Si phases in silicon

Transition metal interaction and Ni-Fe-Cu-Si phases in silicon

Influence of n+ and p+ doping on the lattice sites of implanted Fe in Si

Evolutionary process development towards next generation crystalline silicon solar cells : a semiconductor process toolbox application

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