坩埚石墨化度对SiC单晶生长过程的影响

Effect of Graphitization Degree of Crucible on SiC Single Crystal Growth Process

研究了用改进Lely法制备SiC单晶的过程中坩埚石墨化度对物质传输和晶体生长速度的影响。在不同温度下进行石墨化处理得到了实验所用的坩埚。用XRD方法定量测定了晶体生长前坩埚的石墨化度,并用SEM分析了晶体牛长后坩埚内壁的反应情况。实验结果表明,石墨坩埚在SiC晶体生长过程中是一个非常重要的碳源提供者；当坩埚的石墨化程度较低时,晶体的生长速度快,生长速度由生长温度所控制；随着坩埚石墨化程度的提高,晶体生长速度减慢并由坩埚石墨化度所控制：当石墨化度进一步提高的时候,籽晶被碳化,晶体不能正常生长。

Effects of graphite crucible on the mass transport and the growth rate of the SiC single crystal in fabricating SiC single crystal has been investigated by the seeded sublimation growth method. Different graphitization degrees of the crucibles were obtained by heat treatment at various temperatures between 2100℃ and 2300℃. The crucibles were subjected to SEM observation, XRD investigation, and the graphitization degree was determined quantitatively. The experimental results indicate that the graphite crucible is an important C source provider in the SiC crystal growth. High crystal growth rate is obtained by using the untreated crucibles （corresponding to low graphitization degree）, which contributed to the reaction activity between Si and graphite of the crucible. Increasing the graphitization degree resulted in degradation in crystal growth, even graphitization of the SiC seed crystal.