Papers by Keyword: Multicrystalline Silicon

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Authors: Arthur W. Weeber, Ian J. Bennett, Caroline Tjengdrawira, Machteld W.P.E. Lamers, Agnes A. Mewe, Ingrid G. Romijn, Paul C. de Jong
Abstract: An integrated cell and module technology based on metal-wrap-through (MWT) cells has been developed and demonstrated. 243 cm2 large and 160 µm thin multicrystalline silicon MWT cells were made with a best cell efficiency of 17.9%. From 36 cells with an average efficiency of 17.8% a full-size module was made with an efficiency of 17.0% (aperture area). The module was made using a conductive rear-side foil with conductive adhesive for the interconnection. The module was constructed using a dedicated module manufacturing line that is designed to be able to work with extremely thin cells and provide a high through-put of one 60 cell module per minute.
Authors: V.G. Litovchenko, Andrey V. Sarikov, A.A. Evtukh
Abstract: In this paper, the influence of the gettering treatment on the distribution of diffusion length of minority charge carriers in multicrystalline silicon has been investigated. For the calculation of the parameters of diffusion length distribution, a new method has been proposed based on the mathematical treatment of experimentally measured integrated spectra of surface photovoltage measured by capacitor method (capacitor photovoltage). Obtained results show not only the increase of the average diffusion length as a result of used gettering procedure, but also the decrease of inhomogeneity of its distribution.
Authors: Antti Haarahiltunen, Ville Vähänissi, Marko Yli-Koski, H. Talvitie, Hele Savin
Abstract: Iron precipitation in multicrystalline silicon has been modeled aiming at the optimization of intrinsic gettering of iron in multicrystalline silicon. Iron precipitation during both crystal growth and following phosphorus diffusion gettering (PDG) are simulated and compared to experimental results as the iron precipitate density after these processes is essential in the modeling of intrinsic gettering in multicrystalline silicon solar cell processing. The PDG decreases the density of iron precipitates compared to the as-grown state and as expected the effect is larger at lower initial iron concentrations. Due to this effect the iron precipitation is significantly reduced almost throughout the whole ingot height and it can be concluded that intrinsic gettering has a beneficial effect only in the case of high initial iron concentration, in accordance with the experimental results. The simulated change in interstitial iron concentration as a function of intrinsic gettering temperature suggests the same optimum intrinsic gettering temperature as the experiments. With the given model it is however much easier to find optimal parameters compared to expensive and time consuming experiments.
Authors: Takayoshi Shimura, Takuya Matsumiya, Naoki Morimoto, Takuji Hosoi, Kentaro Kajiwara, Jun Chen, Takashi Sekiguchi, Heiji Watanabe
Abstract: A synchrotron white x-ray microbeam diffraction method was employed to investigate lattice distortion in multicrystalline silicon for photovoltaic cells. The measurements were carried out by scanning the sample, and transmission Laue patterns were observed at each position on the sample. Intensity and position maps of the Laue spots showed the distribution of the crystalline quality of the grains and the bending of the lattice planes. Strain and bending distributions were extracted from an analysis of Laue spots at diagonal positions, and these were compared with those obtained by other techniques.
Authors: Hans Joachim Möller
Authors: Maral Azizi, Elke Meissner, Jochen Friedrich
Abstract: In this work laboratory scale multicrystalline silicon ingots were grown which have been intentionally contaminated with iron in the range between 10 to 400 ppmw by adding FeSi2 to the silicon feedstock. It is shown that an iron contamination at these high levels does not result in a structural breakdown of the columnar grain growth regime because constitutional supercooling could be avoided by strong mixing of the melt in the present crystal growth experiments. The minority carrier lifetime mappings are dominated by the iron contamination and show the distribution of the impurity over the ingot height. The measured values of the specific electrical resistivity show a significant drop from 40 to below 20 Ωcm for a contamination level of 10 ppmw Fe probably due to interactions of iron with thermal donors. At higher contamination levels the specific resistivity increases significantly with increasing iron concentration compared to the 10 ppmw ingot. Above 400 ppmw iron the specific resistivity drops below the initial value for nominally iron free material. These results indicate that interstitial iron shows a donor-like behavior in multicrystalline silicon and precipitated iron decreases the specific resistivity.
Authors: Mohammad Jahangir Alam, Mohammad Ziaur Rahman
Abstract: A comparative study has been made to analyze the impact of interstitial iron in minority carrier lifetime of multicrystalline silicon (mc-Si). It is shown that iron plays a negative role and is considered very detrimental for minority carrier recombination lifetime. The analytical results of this study are aligned with the spatially resolved imaging analysis of iron rich mc-Si.
Authors: J. Knobloch, A. Eyer
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