Phase field calculations of Sn redistribution in GeSn/Si structure after pulsed laser irradiation

An innovative phase field model has been considered to describe the impurity redistribution in a rapid solidification process. This model has been implemented for the description of a complex process in GeSn/Si structure, consisting of the laser heating of solid phase, melting and solidification process. It allowed us to calculate the Sn concentration profile after repeated laser pulses. A significant increase of the Sn concentration near the surface is observed due to the segregation effect accumulated over many laser pulses. The obtained results are in a qualitative agreement with the experimental data for Ge 0.04 Sn 0.96 layer irradiated with nanosecond laser pulses. The differences between these results and those obtained earlier by the molecular beam epitaxy method are discussed.