Dependence of si-faceted dendrite growth orientation on twin spacing and undercooling

Si-faceted dendrites growth orientation as a function of twin spacing and undercooling were investigated by in situ observation, and the mechanisms of the growth behaviors were discussed and clarified. The growth orientation of Si-faceted dendrites strongly depends on the twin spacing and undercooling. For a given undercooling, a dendrite with twin spacing narrower than the critical twin spacing preferentially grows in the «110» direction, whereas growth in the «112» direction preferentially occurs for a dendrite with twin spacing wider than the critical twin spacing. The critical twin spacing for stable faceted dendrite growth increases as the undercooling increases. In the case of low undercooling (∼10 K < δT ≲ 15 K), dendrites dominantly grow in the «112» direction. For high undercooling (∼25 K< δT ≲ 100 K), dendrites preferentially grow in the «110» direction. «110» and «112» growth directions occur with equal frequency for intermediate values of undercooling (∼15 K < δT ≤ 25 K).(Figure Presented)