Short on line course on "Crystallization of Silicon"
Crystallization is the lengthy natural process of formation of highly ordered structure of atoms that is today currently utilized in technology by artificially precipitating solid crystals from a solution, melt or gases to realize crystal structure. The growth of silicon Crystals is perhaps the the most important technological topics of the last decades—the "silicon era" because It has been essential for the development of the electronic devices and solar cells
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This short on line course introduces the main production technologies of monocrystalline silicon, how defects and impurities may be introduced from several sources, the mechanisms for formation of oxygen , one of the main impurities in Czochralski grown silicon, during crystal growth and wafer processing, the numerical simulation of crystal growth processes and correlated physical phenomena, as a powerful tool for the crystal grower, to improve the material properties and at the same time reducing production costs and time
Agenda
Details
Silicon Crystallization and characterization techniques to assess the crystallization quality
Speakers : DI SABATINO LUNDBERG Marisa
Crystallization is one of the first steps during the silicon solar cells value chain. Before silicon solar cells are processed, a silicon ingot is grown either by monocrystalline or multicrystalline processes. During the process, defects may form and impurities may be introduced from several sources. The distribution of defects and impurities, as well as their interaction, is strongly affected by the crystallization process. Thus crystallization parameters play a key role in determining the final ingots quality. In this presentation, the effect of crystallization parameters on ingot quality and the techniques to assess them are reviewed.
Video presentation
Formation of oxygen related defects in Cz-Si
Speakers : JUEL Mari
Oxygen is one of the main impurities in Czochralski grown silicon and can in the wrong state cause large problems and reduction in cell efficiency of silicon based solar cells. A large problem is that the recombination activity of the oxygen related defects often increases during cell processing, resulting in a solar cell with much lower cell efficiency than the expected from the as-grown minority carrier lifetime. One reason for this behaviour is believed to be that small oxygen particles can grow during high temperature solar cell processing steps and in this way change their state.
The presentation will discuss the mechanisms for formation of oxygen related defects in monocrystalline silicon and show examples of which heat treatment and characterisation methods that can be used to identify them.
Video presentation
Numerical simulation of crystallization processes in production of silicon for PV applications
Speakers : BELLMANN Martin P.
Crystal growth from the melt is the most common process which provides the basic crystalline silicon material for photovoltaic applications. Nowadays main production technologies for producing crystalline silicon are the Czochralski pulling technique, directional solidification and to some extend edge-defined film-fed growth.
As crystal growth equipment and experimentation becomes more and more costly, little room remains for improvements by trial and error procedures. The numerical simulation of crystal growth processes and correlated physical phenomena provides a powerful tool for the crystal grower. Common goals are to improve the material properties at the micro- and macro-scale resulting in higher solar cell efficiency, increase of crystal dimensions and at the same time reducing production costs and time
Video presentation