Yu Yue, Liu Botao, Tang Xia, Song Botao, Han Pengfei, Liu Sheng, Gao Bing
The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China.
Materials (Basel). 2021 Dec 22;15(1):54. doi: 10.3390/ma15010054.
The appropriate distribution of temperature in the growth system is critical for obtaining a large size high quality aluminum nitride (AlN) single crystal by the physical vapor transport (PVT) method. As the crystal size increases, the influence of the crucible on the temperature distribution inside the growth chamber becomes greater. In order to optimize the field of temperature and study the specific effects of various parts of the crucible on the large size AlN single crystal growth system, this study carried out a series of numerical simulations of the temperature field of two crucibles of different materials and put forward the concept of a composite crucible, which combines different materials in the crucible parts. Four composite crucible models were established with different proportions and positions of tantalum carbide (TaC) parts and graphite parts in the crucible. Calculations reveal that different parts of the crucible have different effects on the internal temperature distribution. The axial temperature gradient at the crystal was mainly governed by the crucible wall, whereas the temperature gradient was determined by the integrated effect of the crucible lid and the crucible wall in the radial direction. One type of composite crucible was chosen to minimize the thermal stress in grown AlN crystal, which is applicable to the growth of large sized AlN crystals in the future; it can also be used to grow AlN single crystals at present as well.
对于采用物理气相传输（PVT）法获得大尺寸高质量氮化铝（AlN）单晶而言，生长系统中温度的适当分布至关重要。随着晶体尺寸的增大，坩埚对生长室内温度分布的影响变得更大。为了优化温度场并研究坩埚各部分对大尺寸AlN单晶生长系统的具体影响，本研究对两种不同材料的坩埚的温度场进行了一系列数值模拟，并提出了复合坩埚的概念，即在坩埚部件中结合不同材料。建立了四个复合坩埚模型，其中碳化钽（TaC）部件和石墨部件在坩埚中的比例和位置各不相同。计算结果表明，坩埚的不同部分对内部温度分布有不同影响。晶体处的轴向温度梯度主要由坩埚壁决定，而径向温度梯度则由坩埚盖和坩埚壁的综合作用决定。选择了一种复合坩埚来最小化生长的AlN晶体中的热应力，这种坩埚适用于未来大尺寸AlN晶体的生长；目前也可用于生长AlN单晶。
