A Study on Characterization and Prevention of Shadows in Cast Mono‐Crystalline Silicon Ingots

Abstract Dark shadow areas often appear in infrared images of cast monocrystalline silicon (CMC‐Si) ingots. In this work, the formation of shadow and how to avoid it by optimizing the growth process are analyzed. The analysis of scanning electron microscopy & energy dispersive spectroscopy show that the shadows in CMC‐Si are caused by dispersed SiC particles. These particles will further induce a great number of dislocations, subgrain boundaries, and strip‐shaped grains, which decrease the quality and the minority carrier lifetime of CMC‐Si. In addition, an optimized process has proposed and successfully produced a silicon ingot without any shadows. By comparing the traditional and optimized processes, the shadow formation mechanism is studied and found preventing shadow formation by keeping the liquid phase temperature gradient smooth, the maximum crystal growth rate is not more than 1.1 cm h −1 and reducing the value of G L /V below 0.235.