Self-assembled Cd(Se,Te) quantum dots with various Se compositions embedded in the ZnTe matrix are grown by molecular beam epitaxy. A huge redshift of the near band edge emission, from 2.1 eV to 1.5 eV, with an increasing Se content in the dots is observed. It is accompanied by an increase in the excitonic lifetime by the factor of 10. We associate these effects with a gradual change from the direct type I confinement character in CdTe/ZnTe quantum dots to the staggered type II band alignment in the case of Cd(Se,Te)/ZnTe dots. This interpretation is consistent with the micro-photoluminescence study of several individual quantum dots, which reveals a gradual decrease in the biexciton–exciton energy difference with the increasing content of Se in the dots, which leads ultimately to the change from the binding to antibinding character of biexcitons. The latter effect originates, most likely, from the increasing Coulomb repulsion between excitons forming dipoles at the dot/barrier interface.

中文翻译：

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Cd(Se,Te)/ZnTe自组装量子点中I型-II型能带对准跃迁的光学特征

嵌入在 ZnTe 基质中的具有各种 Se 成分的自组装 Cd(Se,Te) 量子点通过分子束外延生长。观察到近带边缘发射的巨大红移，从 2.1 eV 到 1.5 eV，点中的 Se 含量增加。它伴随着激子寿命增加了 10 倍。我们将这些效应与从 CdTe/ZnTe 量子点中的直接 I 型限制特征到 Cd( Se,Te)/ZnTe 点。这种解释与几个单独量子点的微光致发光研究一致，表明随着量子点中硒含量的增加，双激子-激子能量差异逐渐减小，最终导致从结合到抗结合的变化双激子的。