An enhanced cooling design in directional solidification for high quality multi-crystalline solar silicon

An enhanced cooling design for nucleation was proposed for directional solidification based on the enhanced heat transfer through gas flow, and the effects of initial cooling conditions during directional solidification on the quality of multi-crystalline silicon for solar cells were studied. The properties of the grown grains under different initial cooling conditions were measured. The grain size, grain orientations, and the percentage of twin boundaries, as well as minority lifetime and defect density, were affected significantly by the initial cooling. The implementation of this design to a commercial furnace was also discussed, and promising results were obtained.

► An enhanced cooling design using argon flow for nucleation control in mc-Si crystal growth. ► Larger initial cooling, larger {1 1 2} and 〈1 1 0〉 grains with high lifetime and twin density. ► Scale-up to 450 kg furnace with promising results.