Excitonic optical transition in a new II-VI semiconductor superlattice

像ZnSe这样的II-VI半导体不仅因为蓝色半导体激光器的应用而吸引人，而且还因为物理性质而吸引人，例如大的激子结合能。我们提出了ZnSe/MgSe超晶格，并对该超晶格中与激子有关的光学跃迁进行了研究。首先，我们证明了用金属有机气相外延方法生长闪锌矿ZnSe/MgS超晶格。超晶格的晶体性质与初始生长条件密切相关，因此我们考察了金属有机As流等表面清洗条件。通过这些研究，我们可以改善异质界面的原子突变性，在优化的生长条件下生长的超晶格中的单层光致发光峰得到了很好的分辨。在此基础上，用高分辨率X射线衍射仪对超晶格的晶体结构进行了分析。观察到了清晰的超晶格卫星峰。从第0峰的位移可以看出，形成了界面层。这一点随着异质界面生长的中断而得到改善，在直到室温的反射谱中都有明显的激子峰，这表明激子对激子的量子限制增强。该超晶格的光致发光在室温下也表现为激子发光。

II-VI semiconductors such as ZnSe are attractivenot only for the application of blue semiconductor lasers but also from physical properties such as large exciton binding energies. We have proposed ZnSe/MgSSe superiattices and have been working on the exciton related optical transitions in this superlattice.First of all we have demonstrated that the zincblende ZnSe/MgS superlattice can be grown by metalorganic vapor phase epitaxy. The crystalline properties of the the superlattice was critically dependent on the initial growth on GaAs, and therefore the surface cleaning conditions such as metalorganic As flow were examined.With these studies, we could improve the atomic abruptness of the heterointerface and monolayr photoluminescence peaks were well resolved in the ZnSe/MgS superlattice grown with the optimized condition.Based on these growth study, the superlattice crystalline structure was examined with high-resolution X-ray diffraction measurements. Clear superlattice satellite peaks were observed. From the shift of the 0-th peak, we found the formation of the MgSe interface layr. This was improved with growth interruption at the heterointerfaces.Excitonic peaks were clearly observed in the reflection spectra up to room temperature, which indicate the enhancement of quantum confinement on excitons. Photoluminescence from this superlattice was also shown to be excitonic up to room temperature.