Abstract
The temperature field determines the environment in which sapphire crystals are grown, and the molybdenum shield is one of the core components to maintain a stable temperature field. In production, it has been found that the appearance of the molybdenum shield surface changes as the use time increases. In this study, the surface roughness and reflectivity of old and new molybdenum shield samples were tested, and it was found that the surface roughness of the old molybdenum shield was larger and the reflectivity was lower, and the reflectivity of the molybdenum shield was negatively correlated with its surface roughness. Based on the test data, the sapphire crystal growth process was simulated numerically, and the crystal growth experiments were carried out using the old and new molybdenum shield respectively. The old molybdenum shield with low reflectivity would increase the power of the single crystal furnace, change the radial and axis temperature distribution of the temperature field, and make the crystal-melt growth interface too flat and the stress value too large, resulting in increasing the risk of cracking and bubbles in the crystal, leading to the degradation of crystal quality.
Published Version
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