Growth of multicrystalline Si ingots for solar cells using noncontact crucible method without touching the crucible wall

Conventional crystal growth methods using crucibles cannot control the stress caused by expansion due to the solidification of the Si melt. We proposed a noncontact crucible method using a conventional crucible that reduces the stress in Si multicrystalline ingots. In this method, nucleation occurs on the surface of a Si melt using seed crystals, and crystals grow inside the Si melt without touching the crucible walls. Then, the ingots continue to grow while being slowly pulled upward to ensure that the crystal growth remains in the Si melt. A Si ingot with a diameter of 23 cm was obtained in a crucible with a diameter of 30 cm. The maximum solidification ratio in the growth was more than 80%. We have confirmed that such noncontact crucible growth was possible using a conventional crucible.