Solar-grade silicon: current and alternative production routes

Silicon is an important semiconducting and photovoltaic material. It is also widely used for chemical and metallurgical applications. The rapid growth in the demand of solar photovoltaic (PV) cell results in the shortage of solar-grade (SOG) silicon feedstock. Expensive scrap electronic grade (EG) silicon (99.9999999% Si) is commonly used as the raw material to produce SOG-Si (99.9999% Si). Many researchers have reported that relatively inexpensive metallurgical grade (MG) silicon (98-99% Si) can be used as an alternative raw material. The Siemens process, which is based on the hydrogenous reduction of trichlorosilane SiHCl3, is the current dominating production method of SOG-Si. In Australia, there is no available commercial production of SOG-Si production, but the abundance of raw materials such as quartz, combined with the expected growth in photovoltaic silicon demand, has fuelled research in this area. This paper evaluates the progress of SOG-Si production in the world, identifies problems and technical challenges associated with the current and alternative techniques.

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