Cuprous oxide (Cu₂O) is a semiconductor with large exciton binding energy and significant technological importance in applications such as photovoltaics and solar water splitting. It is also a superior material system for quantum optics that enabled the observation of intriguing phenomena, such as Rydberg excitons as solid-state analogue to highly-excited atomic states. Previous experiments related to excitonic properties focused on natural bulk crystals due to major difficulties in growing high-quality synthetic samples. Here, the growth of Cu₂O microcrystals with excellent optical material quality and very low point defect levels is presented. A scalable thermal oxidation process is used that is ideally suited for integration on silicon, demonstrated by on-chip waveguide-coupled Cu₂O microcrystals. Moreover, Rydberg excitons in site-controlled Cu₂O microstructures are shown, relevant for applications in quantum photonics. This work paves the way for the wide-spread use of Cu₂O in optoelectronics and for the development of novel device technologies.

氧化亚铜（Cu ₂ O）是一种具有大的激子结合能并且在光伏和太阳能水分解等应用中具有重要技术重要性的半导体。它也是用于量子光学的高级材料系统，能够观察有趣的现象，例如里德堡激子作为高激发原子态的固态类似物。以前与激子特性有关的实验都集中在天然块状晶体上，这是由于在生长高质量合成样品方面存在重大困难。在此，提出了具有优异光学材料质量和极低点缺陷水平的Cu ₂ O微晶的生长。使用可扩展的热氧化工艺，非常适合在硅上集成，如片上波导耦合铜所示₂ O微晶。此外，显示了在位置控制的Cu ₂ O微观结构中的Rydberg激子，与量子光子学中的应用有关。这项工作为光电子中Cu ₂ O的广泛使用和新型器件技术的发展铺平了道路。