3D-Numerical study of the effect of crystal rotation speed on interface shape in Czochralski growth for photovoltaic applications

Abstract

In this work, we conducted a 3D numerical simulation to investigate the shape of the melt-solid interface during the crystal growth of silicon using the Czochralski technique, which is widely employed in photovoltaic applications. Among the key parameters that influence the quality of the grown monocrystalline is the shape of the crystallization interface. This interface has a main role in determining the structural instability of the silicon ingot during the CZ pulling process. The primary aim of this study is to find the optimal rotation speed that results in a flat shape of the interface, which is conducive to forming a well-ordered atomic structure and thus ensuring superior crystal quality for photovoltaic use. Our findings indicate that, for a crucible with a diameter of 100 mm, an optimal rotation speed of 20 rpm gives a flat shape of the melt-solid interface. According to this study, we find that the Czochralski technique is the process that conserve the flow and the heat transfer of materials in the Cz crucible even for high rotation speed; Our results are in agreement with the experiment results. In our study for the Silicon, the heat transfer in the crucible is symmetrical even applying rotation crystal at high rates ( Vrot = 40 - 50 rpm ).