A finite-element, thermal-capillary model is applied to study solute segregation in the horizontal ribbon growth of silicon. Results show a complicated redistribution of solute into the growing ribbon, with nearly constant composition in the upper portion of the crystal and high levels of solute incorporation in the lower portion. The redistribution pattern is explained by convective flow patterns and interfacial geometry in the system. Lower values of equilibrium partition coefficient and solute melt diffusivity contribute to more inhomogeneous crystal composition. Faster pull rates lead to more pronounced redistribution of solute in the crystal. Paradoxically, the inhomogeneous concentration levels in HRG ribbon may be beneficial; impurities accumulate towards a narrow bottom portion of the crystal, leaving a majority of the crystal relatively pure.
Bibliographical noteFunding Information:
This material is based upon work supported in part by the National Science Foundation , under CBET-0755030 and CBET-1336164 , and the Minnesota Supercomputer Institute . Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. We also express our thanks to Dr. Carl E. Bleil of Energy Materials Research, L.L.C., who was a Co-I in the first phase of this research and who provided significant technical input.
- A1. Computer simulation
- A1. Convection
- A1. Heat transfer
- A1. Segregation
- A2. Edge defined film fed growth
- B2. Semiconducting silicon