Abstract The implementation of GaAs0.8Sb0.2 as CL to obtain type-II strain-coupled InAs MQD structures has been examined and compared to similar structures without Sb or without strain coupling. First, it has been demonstrated that capping with GaAsSb prevents the formation of In-rich agglomerations that hampered the QD formation as it has been observed in the sample without Sb. Instead, it promotes the vertical alignment (VA) of almost all QDs with a high density of QD columns. Second, there is a preferential Sb accumulation over the dots together with an undulation of the growth front, contrary to the observed in the uncoupled structure. In case of a deficient covering of GaAsSb, as occurs for giant QDs, In-rich agglomerations may develop. Each VAQD column consists of a sequence of alternating quantum blocks of pyramid-shaped In(Ga)As separated by GaAsSb blocks that rest over them. These Sb-rich blocks are not homogeneous accumulating around the pyramidal apex like a collar. Between the columns, there is an impoverishment of In and Sb compared to the uncoupled sample. These columns can behave as self-aligned nanowires with type II band alignment between self-assembled InAs and GaAsSb quantum blocks that opens new opportunities for novel devices.

中文翻译：

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Sb 对 II 型应变耦合 InAs/GaAsSb 多量子点结构垂直排列的作用

摘要 将 GaAs0.8Sb0.2 用作 CL 以获得 II 型应变耦合 InAs MQD 结构，并与没有 Sb 或没有应变耦合的类似结构进行了比较。首先，已经证明用 GaAsSb 封盖可以防止形成阻碍 QD 形成的富 In 团聚体，因为它在没有 Sb 的样品中观察到。相反，它促进了几乎所有具有高密度 QD 列的 QD 的垂直对齐 (VA)。其次，与在非耦合结构中观察到的相反，在点上有优先的 Sb 积累以及生长前沿的起伏。在 GaAsSb 覆盖不足的情况下，如巨型 QD 所发生的那样，可能会形成富含 In 的团聚。每个 VAQD 列由一系列交替的金字塔形 In(Ga)As 量子块组成，这些量子块由位于它们上方的 GaAsSb 块分隔。这些富含 Sb 的块体不像项圈一样在锥体顶点周围均匀堆积。在色谱柱之间，与未耦合的样品相比，In 和 Sb 的含量较低。这些列可以表现为自对准纳米线，在自组装 InAs 和 GaAsSb 量子块之间具有 II 型能带对准，这为新型器件开辟了新的机会。