Effect of Mesa Shape on Threading Dislocation Density in Ge Epitaxial Layers on Si after Post-Growth Annealing
Effect of Mesa Shape on Threading Dislocation Density in Ge Epitaxial Layers on Si after Post-Growth Annealing
复制标题
后生长退火后台面形状对Si上Ge外延层螺纹位错密度的影响
DOI：
10.1143/jjap.49.04dg23
复制
发表时间：
2010
影响因子：
1.5
通讯作者：
K. Wada
中科院分区：
文献类型：
--
作者：
Y. Takada;J. Osaka;Y. Ishikawa;K. Wada
研究了硅基锗薄膜中介面形状对线位错密度的影响。从表面蚀刻坑计数中发现，生长后退火降低了Si上Ge台面结构和包层Ge层中的螺纹位错密度。具有垂直侧壁的干蚀刻台地显示出与毯层相同的位错密度。这表明，在干蚀刻台面中，位错密度的降低主要是由于与相反的Burgers矢量的位错湮灭，而位错向台面边缘的运动没有贡献。另一方面，具有倾斜（311）面侧壁的选择性生长台面显示出比毯层更低的位错密度，表明位错可以滑出台面边缘。由于热诱导的剪切应力是位错滑动运动的原因，本研究结果表明，在退火过程中积累的剪切应力方面，选择生长的台地应该与干蚀刻台地不同。应力模拟结果表明，在接近顶缘的地方，热致剪切应力的强度和分布存在较大差异。讨论了热应力的分布与位错密度的减小之间的关系。
The effect of mesa shape on threading dislocation density in Ge epilayers on Si is studied. It is found from the etch-pit counting on the surfaces that the post-growth annealing reduces the threading dislocation densities in Ge mesa structures on Si and in the blanket Ge layers. The dry-etched mesas with vertical sidewalls show dislocation densities identical to those for the blanket layers. This indicates that the reduction in threading dislocation density in the dry-etched mesas is predominantly due to the annihilation of dislocations with opposite Burgers vectors, while the motion of dislocations to the mesa edges does not contribute. On the other hand, the selective-grown mesas with inclined (311) facet sidewalls show lower dislocation densities than those for the blanket layers, indicating that the dislocations can glide out beyond the mesa edges. Since the shear stress thermally induced in Ge is responsible for the dislocation glide motion, the present result suggests that the selective-grown mesas should be different from the dry-etched mesas in terms of the shear stress accumulated during the annealing. Strain simulations for these mesa structures show that the strength and distribution of the thermally induced shear stress are quite different near the top edges between the mesa structures. We discuss the relationship between the distribution of thermal stress and the reduction in dislocation density.
影响因子：
46.9
作者：
Fujimoto, JG
通讯作者：
Fujimoto, JG