(山东大学 晶体材料国家重点实验室， 济南 250100)
摘 要: 采用高纯Si粉和C粉在适宜的温度和压力下合成了多晶SiC粉末， 在此基础上采用升华法在低压高温下条件下生长了大直径6H-SiC单晶， 并根据热力学理论分析了SiC的分解。 结果表明，在2300℃ 附近的生长温度下， Si， Si2C， SiC2是Si-C热力学平衡下的主要物种，其平衡分压比同组分的SiC物种高出3个量级， 因而是升华过程中的主要物种，其质量传输过程直接决定SiC的生长。另外， 采用光学显微镜观察SiC单晶中的生长缺陷，分析了缺陷成因， 提出了碳的包裹体是微管缺陷的重要来源， 而调制掺氮可以抑制部分微管在［0001］方向上的延伸， 并在此分析基础上调整生长参数， 生长出了高质量的6H-SiC单晶。
关键字: 升华法； SiC； 微管
（State Key Laboratory of Crystal Material , Shandong University, Jinan 250100, China）
Abstract:SiC powder was synthesized by using Si and C powder at favorable temperature and pressure. Then silicon carbide crystal was grown by the sublimation method under a low pressure and high temperature region. The decomposition reaction of SiC was simulated according to the thermodynamic theory. The result shows that the dominating species under thermodynamic equilibrium are Si,SiC2 and Si2C at about 2300℃. The equilibrium partial pressures of these three species are three magnitude degrees higher than those of the other species. Therefore, they are the main species during the sublimation process, and their mass flow determines the growth process. Furthermore, crystal defects were observed by optical microscopy. Carbon inclusions are the important origin of micropipes. It was found that the propagation of micropipes along the growth direction could be interrupted by modulation nitrogen doping. 6H-SiC of good quality is obtained after optimizing growth parameters.
Key words: sublimation method； SiC； micropipe
