Li Xinlei, Yang Guowei
MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, People's Republic of China.
Nanotechnology. 2014 Oct 31;25(43):435605. doi: 10.1088/0957-4484/25/43/435605. Epub 2014 Oct 9.
The heteroepitaxial growth of strained islands on a planar substrate offers an attractive route to the fabrication of quantum dots (QDs). To obtain more functions and superior properties, recent efforts have focused on using nanowires (NWs) as substrates to produce attractive structures that combine QDs with NWs. As the lateral size of an NW is large, it is possible that islands are formed on the side walls of the NW. However, no islands exist, and the lateral surface is rather smooth in thin, core-shell NWs. The existing theoretical models on the growth on planar and patterned substrates are not appropriate for the growth transition on the surface with nanoscale curvature. We thus urgently need to understand the basic physics involved in the strain-induced growth on the surface with nanoscale curvature. Here, we established a theoretical model to study the strain-induced growth on the surface, which showed that the Stranski-Krastanov (SK) mode can change to the Frank-van der Merwe (FM) mode due to the limit of the surface to the island's lateral growth. Using the model to investigate the heterostructured core/shell nanowires (NWs), we found, in addition to the SK mode on thick NWs and the FM mode on thin NWs, that there is a multiplex mode on medium NWs which includes the initial layer growth, the intermediate islands' growth and the final layer growth again. The established theoretical model not only explained some puzzling experimental results but also provided useful information to design and control the epitaxial growth on the surface with nanoscale curvature.
在平面衬底上异质外延生长应变岛为量子点（QD）的制备提供了一条有吸引力的途径。为了获得更多功能和优异性能，最近的研究工作集中在使用纳米线（NW）作为衬底来制备将量子点与纳米线相结合的有吸引力的结构。由于纳米线的横向尺寸较大，在纳米线的侧壁上有可能形成岛。然而，在薄的核壳纳米线中不存在岛，并且其侧面相当光滑。现有的关于平面和图案化衬底上生长的理论模型不适用于具有纳米级曲率表面上的生长转变。因此，我们迫切需要了解在具有纳米级曲率的表面上应变诱导生长所涉及的基本物理过程。在此，我们建立了一个理论模型来研究表面上的应变诱导生长，该模型表明由于表面对岛横向生长的限制，斯特兰斯基 - 克拉斯坦诺夫（SK）模式可以转变为弗兰克 - 范德梅尔韦（FM）模式。使用该模型研究异质结构的核/壳纳米线，我们发现，除了厚纳米线上的SK模式和薄纳米线上的FM模式外，中等尺寸纳米线上存在一种多重模式，包括初始层生长、中间岛生长以及再次的最终层生长。所建立的理论模型不仅解释了一些令人困惑的实验结果，还为设计和控制具有纳米级曲率表面上的外延生长提供了有用信息。
