Materials World Network: Engineering the Spintronic Properties of Semiconductor Quantum Dots

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With this Materials World Network award to University of Pittsburgh scientists from US, Brazil, Canada and Argentina will study engineered quantum dot systems that have been specifically tailored for spintronic and quantum information applications, and is co-funded by the Electronic Materials program in the Division of Materials Research and the Americas program in the Office of International Science and Engineering. This collaborative project with scientists from University of Pittsburgh, Laboratorio Nacional de Luz Sincrotron (Brazil), University of Guelph (Canada), and University of Buenos Aires (Argentina) will develop two material systems: InAs:GaAs and Ge:Si quantum dots. Each system has unique strengths and challenges in terms of spintronic applications, and the degree with which these properties can be manipulated through growth. InAs:GaAs quantum dots will be grown using an approach that will create highly monodisperse quantum dots with densities that can be varied over two orders of magnitude. Ge:Si quantum dots will be grown using a novel approach in which SiC nanotemplates are placed controllably on the surface of Si(100), followed by "directed" self-assembly of Ge islands on the templated surface. Characterization of these dots will be performed in a variety of complementary ways, including tunneling microscopy/spectroscopy, photoluminescence/absorption spectroscopy, and capacitance-voltage measurements (to extract the g-tensor of quantum dots as well as determine the electron occupancy). High-resolution x-ray measurements will provide crucial structural information about the internal composition of the quantum dots. Prototype spintronic devices will be developed for producing, manipulating and measuring spin in quantum dots. These simple devices will be used to measure spin coherence times, g-tensor modulation resonance in single quantum dots, and test mechanisms for single electron spin readout (using spin-dependent tunneling measured at microwave frequencies).The proposed research focuses on tailoring the growth of semiconductor quantum dots in order to optimize properties for spintronic and quantum information applications. Control over the properties of quantum dots has been a foremost goal in material science over the last two decades. Spintronics and spin-based quantum information science and technology share widespread international attention, and the proposed collaboration will formalize and strengthen the ties within the Americas. Graduate students are likely to receive the greatest benefit from this international collaborative program. During their trips abroad, students will share their expertise, cultures, approaches to science, and their intellectual and cultural horizons. The bonds fostered within this exchange program are designed to endure throughout an entire professional career.