Study on the Influence of the Pulling Rate on the Axial and Radial Uniformity of Gallium in Czochralski Monocrystalline Silicon Crystal

Gallium-doped single crystal silicon is becoming the mainstream of the photovoltaic market due to their effective suppression of light-induced degradation. However, due to the very low segregation coefficient of gallium in silicon bulk, the uniform doping in silicon ingot is challenging. In this study, the accumulation of gallium at the solid–liquid interface was investigated under the different pulling rates of the crystal. The transfer behavior of gallium from liquid to solid phase was analyzed by using the principle of separation coagulation effect and numerical simulation. The qualified length of the axial resistivity inside the crystal was used to explore the appropriate pulling rate. In addition, the general function relation between the growth height of the crystal and the gallium content was also fitted. Finally, based on the uniformity of radial doping, the best pulling rate, which is in the range of 1.6–1.8 mm/min, was obtained.