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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.
Single-layer and double-layer Ge quantum dots were prepared by ion beam sputtering. By comparing the size and morphology of QDs with different thickness of Si isolation layer and different buried quantum dot density by atomic force microscope, Quantum dots generated by the strain on the surface of the quantum dot wetting layer and the nucleation and embedded strain model to explain it.The experimental results show that the coverage of Ge quantum dots in the Si isolation layer of the distribution of the strain field, The decrease of the thickness of the point wetting layer increases the volume of the point. The strain intensity increases with the decrease of the thickness of the insulating layer, resulting in the change of the shape and size of the surface quantum dots. In addition, the strain also regulates the spatial distribution of surface quantum dots.