Heat and Mass Transfer in an Industrial EFG Silicon Tube Growth System

Progressively expanding of photovoltaic industry has caused worldwide silicon feedstock shortage. The fast growth of high quality thin tubes is critical to achieve high solar cell efficiency while reducing the consumption of raw materials. A previously developed comprehensive two-dimensional global model, has been used to predict electromagnetic induction heating and heat and mass transfer in the entire growth system. To achieve more accurate simulation results, a two dimensional local model is developed to simulate the temperature distribution along the silicon tube and temperature gradient at the solid-liquid interface, which are critical for stable growth, and residual stress. The radiation, convection and conduction heat transfer between silicon tube and environment and treatments of solid-liquid interface movement and solidification latent heat generation at the growth interface are discussed in this paper. Simulation results of the electromagnetic and temperature fields for a large diameter EFG is presented. A one-dimensional dynamic model is used to study the oscillation of silicon tube thickness under different conditions. Parametric studies have been performed to study the effects of pull rate and tube thickness on tube temperature distribution and tube quality. The effects of different carrying gas flow rates will also be investigated. The relationship between the temperature profile along the silicon tube and the silicon tube thickness, pull rate, and gas flow rate is established.