High‐quality multi‐crystalline silicon growth for solar cells by grain‐controlled directional solidification

We report simple ideas for grain control by using active cooling and crucible insulation for high‐quality multi‐crystalline silicon (mc‐Si) growth for solar cells. The method employed an active cooling spot to induce initial dendrite growth, and the solidification front was controlled to be slightly convex through crucible insulation. It was found that the percentage of grains having twins was significantly increased by the present approach. The dislocation density for those grains was also significantly lower. More importantly, the successful improvement showed that the grain size and the minority carrier lifetime increased along the growth direction. And the laser beam induced current (LBIC) measurement also showed much higher quantum efficiency for the twin area.