离子束溅射Ge量子点的应变调制生长

采用离子束溅射技术制备了单层和双层Ge量子点, 通过原子力显微镜对比了不同Si隔离层厚度和不同掩埋量子点密度情况下表层量子点的尺寸和形貌差异, 系统研究了掩埋Ge量子点产生的应变对表层量子点的浸润层及形核的影响, 并用埋置应变模型对其进行解释. 实验结果表明, 覆盖Ge量子点的Si隔离层中分布着的应变场, 导致表层量子点浸润层厚度的降低, 从而增大点的体积; 应变强度随隔离层厚度的减小而增加, 造成表层量子点形状和尺寸的变化; 此外, 应变还调控了表层量子点的空间分布. 关键词： Ge量子点 埋层应变 离子束溅射

Underlying strain-induced growth of the self-assembled Ge quantum-dots prepared by ion beam sputtering deposition

The quantum-dot samples with single Ge layer and twofold stacked Ge layers are prepared by ion beam sputtering deposition. The different sizes and morphologies of quantum-dots are characterized using atomic force microscope technique. The effects of strain from the capped Ge quantum-dots on the upper Ge wetting layer and the nucleation are also investigated by the buried strain model. The results show that the non-uniform strain in the Si spacing layer which caps the buried quantum-dot layer, leads to the decrease of Ge critical thickness in the upper layer, which increases the upper dot size. The strain intensity increases with the decrease of Si spacer thickness, which results in the changes of dot shape and size in the upper layer. Furthermore, the strain also modulates the distribution of upper quantum-dot layer.