Quantum Dot Patterning for Tailored Properties

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Technical: This project seeks fundamental understanding of the evolution of epitaxial quantum dot nanostructures. It is anticipated that the outcome of this research will provide insights on what controls the shape, strain, and chemical composition profile in the dot and its vicinity; what factors drive the evolution of quantum dots under different thermodynamic and kinetic conditions; and how directed-assembly, by patterning, can alter the properties of these structures. This study will benefit from new developments demonstrating that direct x-ray phase retrieval methods can non-destructively probe the 3D structure, chemical and strain distributions of epitaxial quantum dots. The plan is to apply Coherent Bragg Rod Analysis (COBRA) mapping techniques to a variety of quantum dot systems, including self-assembly by Stransky-Krastanov growth and droplet epitaxy, as well as novel site directed assembly methods. In-depth x-ray synchrotron studies of patterned dot arrays will be achieved by Focused Ion Beam patterning as well as nanostructure growth on patterned templates made by electron-beam lithography. Site directed deposition of quantum dots has the potential to greatly improve the compositional and geometrical uniformity of quantum confined materials, compared to self assembled dots?this limitation has been holding back widespread implementation of quantum dots for applications. The combination of state-of- the-art materials growth and deposition with advanced x-ray phase reconstruction techniques is expected to provide the means to control critical growth parameters, quantitatively measure their effects on quantum dot structures, and use this information to engineer desirable properties. Non-Technical: The project addresses basic research issues in a topical area of materials science having high technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new understanding and capabilities for semiconductor quantum dot systems of interest for improving existing semiconductor device technologies, such as lasers, and detectors, especially for telecommunications and solar applications. Quantum dot systems may also be an enabling technology for future areas of application such as quantum computing and single electron devices. The project offers research opportunities for graduate training, including experience at national facilities (Advanced Photon Source), and also for more junior students and under-represented groups to develop their interests in science and engineering. The PIs are heavily involved in outreach activities, from junior high through undergraduate research opportunities. They have integrated hands-on activities which resonate with societal needs; for example, they have planned new curriculum on alternate energy applications, and are working with innovative data sharing informatics.