Three-dimensional global analysis of thermal stress and dislocations in a silicon ingot during a unidirectional solidification process with a square crucible

Single-step directional solidification technology for solar grade polysilicon preparation

“…Firstly, the structure of furnace is symmetrical, so only a quarter of the geometry needs to be considered. Secondly, the convection in the growth system is weak and lacks a dominant heat transfer effect [14,15], so the convection in the silicon as well as in the furnace is ignored. The accurate calculation for thermal conduction, thermal radiation, phase change and thermal stress in the system are performed using the commercial software COMSOL Multiphysics, and the involved governing equations were described in our previous papers [16][17][18].…”

Multicrystalline Silicon Crystal Growth for Photovoltaic Applications

“…For larger ingots, some success has also been reported [2,64,65]. Because the yield stress at high temperature (>1000 C) is only about 9 MPa [68][69][70] for multiplication, the thermal stress in the furnace could be easily higher than this value [71][72][73]. This approach has been adopted widely by industry for the growth of the so-called high performance mc-Si.…”

“…However, if the solidification speed is too high, constitutional supercooling could occur that causes the formation of inclusions, such as SiC, in the grown ingot [42], as discussed for Figure 10.3. The concave interface shape could also generate larger thermal stress in the ingot [71,72]. The solidification speed also affects the interface shape.…”

Transient analysis of the cooling process and influence of bottom insulation on the stress in the multicrystalline silicon ingot

“…Dislocation is a major defect that significantly affects the quality of mc‐Si, thus reduction of dislocation density is necessary to improve performance of solar cells. Formation and multiplication of dislocation in a growing ingot are closely related to thermal stresses and associated strains . It is commonly believed that dislocations usually generate or multiply in the regions where the induced von Mises stress is larger than the critical resolved shear stress (CRSS model).…”