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采用升华法生长调制掺氮的6HSiC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6HSiC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6HSiC晶体的晶格发生畸变,可导致产生新微管。
Nitrogen-doped 6HSiC single crystals grown by sublimation method were grown. The nitrogen-doped fringes of the [0001] longitudinal slits showed that the growth frontier of the crystals gradually changed from the convex shape in the initial growth phase to the nearly flat shape in the subsequent growth phase. It was found that the nearly flat growth front is conducive to the improvement of single crystal quality. Transmission electron microscopy revealed that microtubules could become dissociated and disappeared if the extension direction of the microtube deviates from the [0001] direction of the 6HSiC crystal. The microtubules may also terminate at hexagonal voids or drops of silicon . Nitrogen doping can distort the crystal lattice of 6HSiC crystals and lead to new microtubules.