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A Simplified Approach to Unidirectional Solidification of Silicon

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Background: Silicon is a key ingredient in the creation of photovoltaic (PV) panels for use in solar cells. Polysilicon (polycrystalline silicon) is the market leading form of silicon for PV applications. Polysilicon is traditionally produced using the Siemens process. However the Siemens process is relatively expensive. This has created increased interest in the use of “upgraded metallurgical-grade silicon” (UMG) as a replacement for the Siemens process. Creation of UMG involves a key purity-enhancing step called unidirectional solidification (UDS) of silicon. Technology Description: This method is a simplified approach to performing unidirectional solidification of silicon for the creation of upgraded metallurgical-grade silicon for use in photovoltaics for solar energy production. Applications: This technology is used to affordably and efficiently purify or “upgrade” cheaper metallurgical-grade silicone into upgraded metallurgical-grade silicon for use in photovoltaic solar cells. The resulting product upgraded metallurgical silicon is a cheaper alternative to polysilicon created through the traditional Siemens process yet it still retains a high level of efficiency.


This method is more efficient and affordable than existing methods unidirectional solidification methods for producing upgraded metallurgical silicon for photovoltaic applications. This process reduces the concentration of undesirable metallic elements in the silicon such that subsequent processing yields high purity silicon needed for PV applications. It does so while using less than one tenth the energy of traditional unidirectional solidification methods and is more than ten times faster than existing methods. Additionally equipment and labor costs are greatly decreased.

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