Transition from continuous to lateral growth for Ge crystal in undercooled Ge74Ni26 alloy melts

Through introducing Si clusters onto an undercooled Ge74Ni26 alloy droplet, which was undercooled in B2O3 flux, the free growth of a Ge crystal was realized from the surface to the center of the sample. The faceted to non-faceted transition occurred with increasing undercooling. Furthermore, the non-faceted dendrites could be changed back into faceted structure when the transient undercooling was lower than a certain value. Combining the results of pure Ge and Ge-Sn and Ge-Si dilute alloys with that of Ge74Ni26, the faceted to non-faceted transition was a general effect of undercooling for these systems and the critical undercooling for the growth mode transition was decreased with the addition of solutes.