Solar grade silicon production: A review of kinetic, thermodynamic and fluid dynamics based continuum scale modeling

The rapid growth in silicon photovoltaics deployment has led to increased research focus on the energy and capital intensive refining of solar grade silicon for improved environmental, production and economic benefits. As this process consists of a number of steps taking place in multi-phase reacting systems with complex fluid and energy flows, models can be an important tool for mechanistic understanding, design and optimization. This paper reviews models for the most widely implemented refining techniques and classifies them into two broad categories; those relating to the synthesis of volatile Si based compounds and those relating to the deposition of volatile silicon based compounds. Within each category, models are further divided according to the reactor type or physical process which they are examining. These models typically use computational techniques with various combinations of theory for obtaining chemical thermodynamics, chemical kinetics, fluid mechanics and heat and mass transfer information for a system. The system definition, main assumptions, computational techniques and main results for each study are presented. There is also a brief review of ab initio atomistic studies for this area along with a discussion for future research. This work should help researchers in selecting appropriate physical and chemical models for investigating solar grade silicon refining or further developing their own models.