Science and Schema for Directed Self-Assembly of Heteroepitaxial Quantum Dot Crystals Near the Intrinsic Length Scale

非技术描述：合成量子点介晶体，即嵌入在基体材料中的量子点（QDs）的三维（3D）周期阵列，代表了一种与纳米电子学，热电学，光电子学和磁学设计新材料相关的策略，这些领域对我们的技术型经济至关重要。该项目旨在为与各种3D周期性量子点系统相关的定向自组装的特定方法建立更深入的科学基础，这些系统通常是电子材料研究和开发的核心。这种类型的合成具有达到前所未有的长度尺度的巨大潜力。探讨了高度管制的纳米结构对所得材料性能的影响。包括课程开发和纳米日在内的外展活动与研究项目相结合。技术描述：本研究项目的重点是合成量子点介晶的生长。这些人造材料有望具有新颖和改进的性能。这项研究工作建立在首席研究员最近在硅衬底上创建二维外延锗量子点阵列的成就之上。这些高度均匀的阵列是由纳米级表面模板上的定向自组装形成的。模板要么是周期性的表面形貌，要么是纳米级的“压力源”，由直接写入技术创建。二维量子点阵列作为“种子晶体”，通过额外生长由Si层间间隔层分隔的Ge点层来形成三维介晶。不需要额外的模板。最终目标是控制自组装过程接近固有的，限制长度尺度与应变驱动量子点自组装相关。所得材料的结构特征，并探讨其潜在的新型电子和热输运。

Non-technical Description: Synthetic quantum dot mesocrystals, i.e., three-dimensional (3D) periodic arrays of quantum dots (QDs) embedded in a matrix material, represent one strategy pertinent to designing new materials for nanoelectronics, thermoelectrics, optoelectronics, and magnetics, all areas that are critical to our technology-based economy. The project aims at establishing a deeper scientific basis for a specific approach to directed self-assembly relevant to various 3D periodic QDs systems that are often at the heart of electronic materials research and development. This type of synthesis has a great potential to reach unprecedented length scales. The effects of the highly-regimented nanostructure control on the resulting materials properties are explored. The outreach activities including curriculum development and the NanoDays are integrated with the research program. Technical Description: This research project focuses on the growth of synthetic quantum dot mesocrystals. These artificial materials are expected to have novel and improved properties. This research effort builds on the principal investigator's recent accomplishments in creating two-dimensional arrays of epitaxial Ge quantum dots on Si substrates. These highly uniform arrays formed by directed self-assembly on nanoscale surface templates. The templates are either periodic surface topography, or nanoscale "stressors," created by direct-write techniques. The two-dimensional quantum dot arrays serve as "seed crystals" for the formation of the three-dimensional mesocrystal by additional growth of Ge dot layers separated by Si interlayer spacers. No additional templating is required. The ultimate goal is to control self-assembly processes close to the intrinsic, limiting length scales associated with strain-driven quantum dot self-assembly. The resulting materials are structurally characterized, and their potential for novel electronic and thermal transport is explored.