Evolution of spirals during molecular beam epitaxy of GaN on 6H-SiC(0001)
Evolution of spirals during molecular beam epitaxy of GaN on 6H-SiC(0001)
复制标题
DOI：
10.1103/physrevb.66.155330
复制
发表时间：
2002-10-15
影响因子：
3.7
通讯作者：
Li, L
中科院分区：
文献类型：
--
作者：
Cui, Y;Li, L
用原位扫描隧道显微镜研究了在6 H-SiC（0001）衬底上分子束外延生长GaN薄膜过程中螺旋线的演化。结果发现，位错出现在薄膜表面，产生直台阶与取向沿着方向与10（10）cm（-2）的密度为40 nm厚的膜。在随后的生长过程中，这些直台阶缠绕在位错周围，并发展成螺旋，对于100 nm厚的膜，密度为10（9）cm（-2）。螺旋可分为三种类型：单臂，互锁双臂和闭环。前两种类型源自一端固定的台阶，第三种类型源自两端固定的台阶。当膜厚大于200 nm时，这些螺旋进一步演变成密度为10（7）cm（-2）的螺旋土丘。基于Burton、Cabrera和Frank理论，提出了一个模型来解释不同类型螺旋的形成及其密度的减小。
Evolution of spirals during molecular beam epitaxy growth of GaN films on 6H-SiC(0001) was studied by in situ scanning tunneling microscopy. It was found that dislocations emerge at the film surface, creating straight steps with orientation along directions with a density of 10(10) cm(-2) for 40-nm-thick films. During subsequent growth, these straight steps wind around dislocations and develop into spirals with a density of 10(9) cm(-2) for 100-nm-thick films. The spirals can be classified into three types: single arm, interlocking double arm, and closed loop. The first two types originate from steps with one end pinned, and the third type results from steps with both ends pinned. At film thickness larger than 200 nm, these spirals further evolve into spiral mounds with a density of 10(7) cm(-2). Based on the Burton, Cabrera, and Frank theory, a model is proposed to explain the formation of different types of spirals and the reduction of their densities.