EFFECTS OF GEOMETRICAL PARAMETERS IN THE DS METHOD FOR THE GROWTH OF LARGE SIZED POLYCRYSTAL SILICON

摘要

Polycrystalline silicon (Si) wafers share more than 60% of the photovoltaic market due to its cost advantage compared to the mono-crystalline silicon wafers. Several solidification processes have been developed by industries, including casting, heat exchanger method and electromagnetic casting. However, the market growth using mono-and polycrystalline Si wafers might be saturated due to the shortage of Si feedstock. One of the methods to solve this issue is to make higher quality polycrystalline Si wafers which are capable of producing higher efficiency solar cells. In this work, the effects of changing several geometrical parameters were evaluated to improve the directional solidification (DS) method and to satisfy the above-mentioned main targets. The developed DS method has the advantages of the small heat loss, short cycle time and efficient directional solidification. Based on the fluid dynamics model, the numerical simulation was performed on the thermal characteristics during the DS process. Using a commercial CFD code, Fluent, the heat transfer characteristics in the DS system are calculated, and the results are graphically depicted.