Defects of Multi-Plate Sapphire Grown from EFG Technique

Abstract

Abstract: Multi-plate sapphire crystals were grown by EFG technique. Micro-laser Raman spectrum and ICP-AES were used to identify the chemical composition of the matters in bubbles, showing that these matters may contain sulphur. Growth striations at the surface of the crystal were concerned with fluctuation of growth rate and temperature as well as the working accuracy of the die. Chemical etching test shows that the crystal has a dislocation density of 4.2×10⁴ cm^-2 and there is no low angle grain boundary defect. X-ray rocking curve measurement shows a single peak with FWHM of 70.63″. Owing to graphite heat shade, the crystal contains F and F⁺ centers. The transmittance of the crystal is over 80% at light wavelength from 400 nm to 3 000 nm. Annealing the crystal in air can reduce optical absorption caused by color centers. The results of this paper are useful to theoretical study on formation of defects in sapphire and technical improvement on EFG sapphire industury.

Key words: sapphire, EFG, crystal growth, defect, bubble, color center

CLC Number:

O734

CHEN Weichao, LUO Ping, WANG Qingguo, TANG Huili, XUE Yanyan, DUAN Jinzhu, WANG Qinfeng, LEI Zhenlin, XU Jun. Defects of Multi-Plate Sapphire Grown from EFG Technique[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2021, 50(4): 741-746.

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