Nucleation and Crystal Growth of Si1-xGex Melts during Rapid Cooling Processes: A Molecular-Dynamics Study

To clarify the growth mechanism of the lateral growth of Ge in the rapid-melting-growth process, two types of molecular-dynamics simulation were investigated in this study. One was the nucleation of Si1-xGex (0 \leq x \leq 1) from supercooled melts, and the other is the growth rate of supercooled Si1-xGex melts using a crystalline Si1-xGex seed. The incubation time is found to be minimum at approximately 0.70 T_{\text{m}} (T_{\text{m}}: melting temperature for Si1-xGex). No nucleation was found when the temperature was higher than 0.75 T_{\text{m}}. The crystal growth rates of Si1-xGex peaked between 0.90 T_{\text{m}} and 0.94 T_{\text{m}} for both the [100] and [111] orientations. These results suggest that 0.90 T_{\text{m}} to 0.94 T_{\text{m}} of Si1-xGex (x = 1) is an optimum temperature range to grow crystalline Ge in the rapid-melting-growth process.