Formation and Strain Analysis of Stacked Ge Quantum Dots With Strain-Compensating Si1-xCx Spacer
Formation and Strain Analysis of Stacked Ge Quantum Dots With Strain-Compensating Si1-xCx Spacer
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具有应变补偿 Si1-xCx 间隔物的堆叠 Ge 量子点的形成和应变分析
DOI：
10.1002/pssc.201700197
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
K. Washio
中科院分区：
文献类型：
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作者：
Y. Itoh;T. Kawashima;K. Washio
为了将 Ge 量子点 (QD) 堆叠在多层结构中，而不会使 QD 发生不必要的增大，研究了 Si1−xCx 间隔物对嵌入 QD 应变补偿的影响，以及亚单层 (ML) 碳 (C) 介导对 Si1−xCx 间隔物上 Volmer-Weber (VW) 模式 Ge QD 形成的影响。在Si1-xCx/Ge/Si(100)结构中，嵌入QD的晶格旋转在x=≥0.015时保持约80%。由于生长在 QD 周围的 Si 衬底表面上的 Si1-xCx 层的拉伸应变，这保持了高弛豫状态。此外，通过开尔文探针力显微镜分析，发现0.25 ML及以上的亚ML C介导可有效在Si1−xCx间隔物上形成VW模式Ge QD。这是因为通过C介导促进量子点形成的细分效应在Si1−xCx表面上也有效。当C = 0.25和0.5 ML时，第二量子点的直径和密度分别约为22nm和1.5 × 1011cm−2。这些结果为在多层结构中堆叠 VW 模式 Ge 量子点铺平了道路，而无需扩大量子点。
To stack Ge quantum dots (QDs) in a multilayer structure without undesirable enlargement of the QDs, the effects of both Si1−xCxspacer on a strain compensation of the embedded QDs and a sub‐monolayer (ML) carbon (C) mediation on a formation of the Volmer‐Weber (VW)‐mode Ge QDs on the Si1−xCxspacer were investigated. In a Si1−xCx/Ge/Si(100) structure, lattice rexation of the embedded QDs was kept about 80% atx= 0.015. This maintaining the state of high relaxation attributed to a tensile strain from the Si1−xCxlayer grown on a surface of a Si substrate around the QDs. In addition, by utilizing an analysis of Kelvin probe force microscopy, it was revealed that the sub‐ML C mediation of 0.25 ML and over is effective to form the VW‐mode Ge QDs on the Si1−xCxspacer. This is because the promotion of subdivision effect for the formation of the QDs via C mediation was also effective on the Si1−xCxsurface. At C = 0.25 and 0.5 ML, diameter and density of second QDs were about 22 nm and 1.5 × 1011cm−2, respectively. These results pave the way to stack the VW‐mode Ge QDs in the multilayer structure without enlargement of the QDs.