Separation mechanism of bulk Si from Si–Sn melt via upwards directional solidification based on the density difference

Abstract

There is no systematic study on the separation mechanism of bulk Si from Si–Sn melt by directional solidification, although the system has many outstanding advantages. In this work, the influence of alloy composition and cooling rate on the quality of grown bulk Si were studied. The length of the mushy zone increased with the composition, and the stable convex interface only occurred at the composition of Si higher than 50 at.%; As for the composition of Si–12.5 at.% Sn, the convex interface became flatter. The separation effect deteriorated rapidly with the cooling rate. The evolution of the crystal growth process and the transfer of the interface were simulated, which predicts the shape of the interface and explains the residual Sn trapped in bulk Si.