Critical undercoolings for the transition from the lateral to continuous growth in undercooled silicon and germanium

The effects of crystal-liquid interface energy and undercooling on a crystal-liquid interface structure and the growth mode of undercooled semiconductors have been investigated. A factor to predict the structure of the solid-liquid interface has been identified. Criterions expressed as the critical nucleation undercoolings (ΔT*₁ and ΔT*₂) and kinetic undercoolings (ΔT*_K1 and ΔT*_K2) to judge the transition of growth mode in undercooled semiconductor have been developed. The growth mode of a semiconductor is a lateral one when nucleation undercooling is lower than ΔT*₁ or kinetic undercooling is lower than ΔT*_K1, a continuous one when nucleation undercooling is higher than ΔT*₂ or kinetic undercooling is higher than ΔT*_K2, and an intermediary one in the nucleation undercooling region from ΔT*₁ to ΔT*₂ or kinetic undercooling region from ΔT*_K1 to ΔT*_K2. The critical undercoolings for the growth transition predicted from the present criterions for silicon and germanium are in very good agreement with the experimentally measured results.