微管在6H-SiC单晶生长过程中的演化

采用升华法生长调制掺氮的6H-SiC单晶，其0001]方向纵切片的掺氮条纹表明，晶体的生长前沿由初始生长阶段的凸形逐渐变成了后续生长阶段近似平坦的形状。发现近似平坦的生长前沿有利于单晶质量的提高。透射光学显微镜观察发现，若微管的延伸方向与6H-SiC晶体的0001]方向偏离角度较大时，微管变得不稳定而离解消失；微管也可终止于六边形空洞或硅滴处。氮元素掺杂可使6H-SiC晶体的晶格发生畸变，可导致产生新微管。

MICROPIPE EVOLUTION DURING THE GROWTH PROCESS OF 6H- SiC MONOCRYSTALLINE

The modulated nitrogen-doped 6HSiC monocrystalline was grown by sublimation method. The nitrogen-doped striations in axial-cut slice along \ direction of the as-grown crystal show that the convex growth front at the initial growth stage changes gradually into nearly flat growth front at the subsequent growth stages. It is found that the nearly flat growth front is in favor of improving the crystal quality. The observations through optical microscopy in the transmission mode show that some micropipe tends to be unstable and dissociate when the deviation angle between the extending direction of micropipe and \ direction of 6HSiC crystal becomes larger. In addition, some micropipe can also end at a hexagonal void or silicon droplet. Nitrogen-doping can induce lattice distortion of 6HSiC crystal, which results in the generation of a new micropipe.