Seed-assisted growth of high-quality multi-crystalline silicon in directional solidification

An approach to grain control using seed-assisted growth in directional solidification (DS) is reported in this paper. Proper multi-crystalline silicon seeds at the bottom of the crucible provided numerous fine nucleation points for the controlled grain growth in an optimized hot-zone. Low dislocation density was observed with large numbers of uniform small grains in the silicon ingot, although the grain size increased with crystal growth. Crystals produced using seed-assisted growth showed a higher and more uniform minority carrier lifetime with a much lower dislocation multiplication rate. A higher average solar cell conversion efficiency of about 0.5% in absolute value was obtained in the seed-assisted grown silicon in comparison with that in the seedless silicon under the same cell fabrication process. •Multi-crystalline silicon seeds for externally seeded growth process were performed.•We carried out a study in an optimized hot-zone for seed-assisted growth.•Uniform grains sizes with low dislocation density and propagation rate was obtained.•Minority carrier lifetime with high values and uniform distribution can be achieved.•The solar cells with high conversion efficiency were achieved in the seeded ingot.