A Simplified Approach to Unidirectional Solidification of Silicon

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.

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.

Applications:

• Affordably and efficiently purify or “upgrade” cheaper metallurgical-grade silicone into upgraded metallurgical-grade silicon for use in photovoltaic solar cells

Advantages:

• More efficient and affordable than existing methods
• Process reduces the concentration of undesirable metallic elements in the silicon such that subsequent processing yields high purity silicon needed for PV applications. 
• Uses less than one tenth the energy of traditional unidirectional solidification methods,
• More than ten times faster than existing methods
• Reduced equipment and labor costs