We demonstrate a new quantum-confined semiconductor material based on GaSb quantum dots (QDs) embedded in a single-crystalline AlGaSb matrix by filling droplet-etched nanoholes. The droplet-mediated growth mechanism allows formation of low QD densities required for non-classical single-QD light sources. The photoluminescence (PL) experiments reveal that the GaSb QDs have an indirect–direct bandgap crossover at telecom wavelengths. This is due to the alignment of the Γ and L valleys in the conduction band as a result of the quantum confinement controlled by the dimensions of the nanostructure. We show that in the direct bandgap regime close to 1.5 µm wavelength, the GaSb QDs have a type I band alignment and exhibit excitonic emission with narrow spectral lines and very low inhomogeneous broadening of PL emission owing to the high material quality and dimensional uniformity. These properties are extremely promising in terms of applications in infrared quantum optics and quantum photonic integration.

中文翻译：

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在电信范围内具有间接-直接带隙交叉的高度均匀的 GaSb 量子点

我们展示了一种基于 GaSb 量子点 (QD) 的新型量子限域半导体材料，该材料通过填充液滴蚀刻的纳米孔嵌入单晶 AlGaSb 基质中。液滴介导的生长机制允许形成非经典单 QD 光源所需的低 QD 密度。光致发光 (PL) 实验表明 GaSb QD 在电信波长处具有间接-直接带隙交叉。这是由于纳米结构尺寸控制的量子限制导致导带中Γ和L谷的对齐。我们表明，在接近 1.5 µ的直接带隙范围内在高波长下，由于高的材料质量和尺寸均匀性，GaSb量子点具有I型能带排列，并显示出具有窄光谱线的激子发射和极低的PL发射不均匀展宽。这些特性在红外量子光学和量子光子集成方面的应用非常有前景。