Epitaxy of intra-plane ordered (In,Ga)N monolayers towards single photon emission

单光子发射体有望在量子通信、线性光量子计算和密码学中作为量子比特。由于它们的热稳定性和化学稳定性，它们从可见光到紫外光谱范围的宽波长可调谐性（In，Ga，Al）N量子点是此类器件的最有希望的候选者。尽管在生长量子点方面取得了成功，在2014年工作温度高达300 K，但固有的压电场、合金波动、活性区的尺寸和形状控制对在明确定义的波长下快速有效地产生单光子通量提出了严峻的挑战。这些问题严重降低了自组织量子点用于可扩展系统的潜力，因为每个量子点实际上是一个单独的结构。该项目的科学使命是通过探索（In，Ga）N单分子膜作为单光子发射的位点控制纳米线的活性区来解决这些问题。取决于生长条件，（In，Ga）N单层可以在层内生长有铟和镓原子的有序配置。这大大减少了空间合金成分波动，从而减少了发射的不均匀加宽。本计画的最终目标是利用自上而下的方法，将有序的（In，Ga）N单分子层嵌入相同形状的奈米线中。这使得三维电荷载流子限制，允许单光子发射的离散能级。由于有序的（In，Ga）N单层的良好定义的组成和量子线的均匀形状，这样的量子点成为均匀的实体。上述目标将通过莱布尼茨晶体生长研究所（IKZ）和中国北京大学（PKU）之间的双边合作来实现。我们的目标是将分子束外延（MBE）领域的丰富能力组合与通过透射电子显微镜（TEM）进行的高级结构分析技术相结合。在这一框架内，两个机构将受益于相互合作，因为它们可以分别获得独特的表征方法和样品，从而扩大各自领域的知识。

Single photon emitters hold the promise to serve as quantum bits in quantum communication, linear optical quantum computing and cryptography. Due to their thermal and chemical stability, their wide wavelength tunability from the visible to the ultraviolet spectral range (In,Ga,Al)N quantum dots are the most promising candidates for such devices. Despite the success in growing quantum dots, operating up to 300 K in 2014, the inherent piezoelectric fields, alloy fluctuations, size and shape control of the active zone pose severe challenges with respect to fast and efficient generation of a single photon flux at a well-defined wavelength. These issues severely decrease the potential of self-organized QDs for scalable systems since each QD is practically an individual structure. The scientific mission of this project is to tackle these issues by exploring (In,Ga)N monolayers as the active zone in site controlled nanowires for single photon emission. Depending of the growth conditions, (In,Ga)N monolayers can be grown with an ordered configuration of Indium and Gallium atoms within the layer. This strongly reduces spatial alloy composition fluctuations and thus the inhomogeneous broadening of the emission. The final goal of this project is to embed ordered (In,Ga)N monolayers in identically shaped nanowires by means of the top-down approach. This enables three-dimensional charge carrier confinement, permitting discrete energy levels for single photon emission. Due to the well-defined composition of the ordered (In,Ga)N monolayers and the uniform shape of the quantum wires, such quantum dots become uniform entities. These above-mentioned objectives will be achieved by means of a bilateral collaboration between the Leibniz-Institute for Crystal Growth (IKZ) and the Peking University (PKU) in China. We aim to unify a rich portfolio of competencies in the field of molecular beam epitaxy (MBE) with high-level structural analysis techniques carried out by means of transmission electron microscopy (TEM). Within this framework, both institutions will benefit from a mutual collaboration due to access to unique characterization methods and samples respectively, allowing them to expand the knowledge in their respective fields.