Germanium partitioning in silicon during rapid solidification

Pulsed laser melting experiments were performed on Ge_xSi _1-x alloys (x≤0.10) with regrowth velocities ranging from 0.25 to 3.9 m/s. Analysis of post-solidification Ge concentration profiles, along with time-resolved melt depth measurements, allowed determination of the liquid-phase diffusivity D_l for Ge in Si and the dependence of the Ge partition coefficient k on interface velocity v. A D_l of 2.5×10 ^-4 cm²/s was measured. The k vs v data were analyzed using various models for partitioning, including both the dilute and nondilute Continuous Growth Models (CGM). Extrapolating to zero velocity using the partitioning models, an equilibrium partition coefficient of approximately 0.45 was obtained. Best fitting of partitioning data to the nondilute CGM yields a diffusive speed of 2.5 m/s. These measurements quantify previous indications of partitioning observed in other studies of pulsed laser processed Ge _xSi_1-x alloys.