Study of Size, Shape, and Etch pit formation in InAs/InP Droplet Epitaxy Quantum Dots
Study of Size, Shape, and Etch pit formation in InAs/InP Droplet Epitaxy Quantum Dots
复制标题
DOI：
10.1088/1361-6528/ac659e
复制
发表时间：
2022-07-23
期刊：
影响因子：
3.5
通讯作者：
Koenraad, Paul M.
中科院分区：
文献类型：
--
作者：
Gajjela, Raja S. R.;van Venrooij, Niels R. S.;Koenraad, Paul M.
利用截面扫描隧道显微镜（X-STM）研究了金属有机物气相外延液滴外延（DE）和Stranski-Krastanov（SK）InAs/InP量子点（QD）。我们提出了一个原子尺度上的量子点的结构特征的比较，证明了这两种生长方法的DE产生更均匀和形状对称的量子点。DE和SKQD都被发现是截断的形，具有大而尖锐的顶面。我们首次报道了InAs/InP DEQD中原子级分辨率的局部蚀坑的形成。我们详细讨论了液滴蚀刻机制，以了解DEQD下的蚀刻坑的形成。通过k中心点p理论，总结了腐蚀坑的大小和位置对精细结构分裂（FSS）的影响。进行有限元（FE）模拟，以适应实验的外向弛豫和晶格常数剖面的解理量子点。量子点的组合物估计是通过结合FE模拟和X-STM结果获得的纯InAs。在DEQD中观察到{136}和{122}侧面的优先形成。从As-P表面交换DE润湿层的形成进行了比较与标准SKQD润湿层。在这项工作中进行的详细的结构表征提供了有价值的反馈，进一步生长优化，以获得量子点与量子技术中的应用，甚至更低的FSS。
We investigated metal-organic vapor phase epitaxy grown droplet epitaxy (DE) and Stranski-Krastanov (SK) InAs/InP quantum dots (QDs) by cross-sectional scanning tunneling microscopy (X-STM). We present an atomic-scale comparison of structural characteristics of QDs grown by both growth methods proving that the DE yields more uniform and shape-symmetric QDs. Both DE and SKQDs are found to be truncated pyramid-shaped with a large and sharp top facet. We report the formation of localized etch pits for the first time in InAs/InP DEQDs with atomic resolution. We discuss the droplet etching mechanism in detail to understand the formation of etch pits underneath the DEQDs. A summary of the effect of etch pit size and position on fine structure splitting (FSS) is provided via the k center dot p theory. Finite element (FE) simulations are performed to fit the experimental outward relaxation and lattice constant profiles of the cleaved QDs. The composition of QDs is estimated to be pure InAs obtained by combining both FE simulations and X-STM results. The preferential formation of {136} and {122} side facets was observed for the DEQDs. The formation of a DE wetting layer from As-P surface exchange is compared with the standard SKQDs wetting layer. The detailed structural characterization performed in this work provides valuable feedback for further growth optimization to obtain QDs with even lower FSS for applications in quantum technology.