Numerical study of the effects of crucible movement on the Ge growth process in an inductive Czochralski furnace

Abstract

The Czochralski (CZ) method is widely used for growing high-purity germanium (Ge) crystals, essential for infrared optics, radiation detectors, and high-mobility transistors. However, thermal stress accumulation, dislocation formation, and unstable growth interfaces remain significant challenges in germanium crystal fabrication. This study presents a numerical investigation of the impact of crucible movement on temperature distribution, melt convection, stress accumulation, and defect formation in CZ germanium growth. Results show that a moving crucible improves temperature uniformity, reducing radial thermal gradients that contribute to stress-induced defects. Melt convection patterns are stabilized, preventing undercooling at the crucible bottom and ensuring more uniform heat distribution. The crystal-melt interface remains smoother, reducing the formation of slip bands and stacking faults—defects that degrade electrical and optical performance in germanium devices. Furthermore, von Mises stress analysis confirms that crucible movement significantly lowers stress accumulation, decreasing dislocation density in the grown crystal. These findings align with experimental studies on germanium CZ growth and provide practical process optimizations for improving semiconductor-grade germanium crystal quality. The results have direct applications in infrared imaging, space solar cells, and high-speed electronic devices, where defect-free germanium is essential.