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

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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.