多片导模法蓝宝石晶体的缺陷研究

使用导模法(EFG)生长了多片a面蓝宝石晶体。显微拉曼光谱结合电感耦合等离子体发射光谱(ICP-AES)测试得出晶体的气泡中可能存在含S化合物。晶体表面明显的生长条纹主要与温度、生长速度的波动以及模具的加工精度有关。化学腐蚀分析表明晶体位错密度在4.2×10⁴ cm^-2,未存在小角度晶界缺陷,双晶摇摆曲线半峰宽(FWHM)为70.63″。由于采用石墨保温材料,晶体中存在F心与F⁺色心。晶体在400~3 000 nm波段透过率高于80%,空气中退火后可减弱色心吸收。本文研究结果可为蓝宝石晶体缺陷形成理论研究提供参考,也可为导模法蓝宝石工业生产技术改进提供借鉴。

Defects of Multi-Plate Sapphire Grown from EFG Technique

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.