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Sigma Aldrich Lecture: “Epitaxy by Design: Epitaxial Growth of Dissimilar Materials”
October 30, 2019 at 11:00 AM - 12:00 PM
Abstract: The ability to integrate dissimilar materials with different crystal structures and properties enables heterostructures to be developed with new functionality well beyond the normal band gap engineering offered by semiconductor heterostructures. The combination of metals, semiconductors, insulators, magnetic, piezoelectric, structural and phase change materials offers the potential for nearly limitless control of device properties. Heusler compounds, for example, are of great interest due to their multifunctional properties including metallic, ferromagnetic, half metallic, semiconducting and potentially topological properties. Heterostructures of ferromagnetic materials with insulators and semiconductors have revolutionized spintronic devices.
Semiconductors are an ideal choice for substrates for dissimilar materials epitaxial growth because of their wide range of lattice parameters, high quality, readily controlled electrical and optical properties and the availability of large area substrates at a reasonable cost. The control of strain and lattice matching, interfacial bonding and reactions is important for the growth and properties of dissimilar materials heterostructures.
In this presentation, results for the molecular beam epitaxial growth of metallic compound/III-V semiconductor heterostructures with designer properties will be discussed. High efficiency electrical spin injection and detection in magnetic Heusler/GaAs contacts, tuning of the spin polarization, as well as the ability to tune the electronic and magnetic properties of Heusler compounds through alloying will be presented. The focus of the presentation will be on understanding the growth and properties of dissimilar materials with emphasis on Heusler compound/III-V compound semiconductor heterostructures. These studies have aimed at tailoring of interfacial and material properties of these dissimilar materials heterostructures for targeting novel applications including spintronics and topological quantum computing.
Chris Palmstrøm
Professor of Computer Engineering and Materials, University of California, Santa Barbara
Chris Palmstrøm is a Professor in the Electrical and Computer Engineering and the Materials Departments at the University of California, Santa Barbara. His research involves atomic level control and interface formation during molecular beam and chemical beam epitaxial growth of metallic compounds, metal oxides and compound semiconductors. He received his B.Sc. in physics and electronic engineering and Ph.D. in electrical and electronic engineering from the University of Leeds. After being a Lecturer in Norway and a Research Associate at Cornell, he joined Bellcore as a Member of Technical Staff in 1985. From 1994-2007 he was a Professor in the Department of Chemical Engineering and Materials Science at the University of Minnesota and in 2004 became the Amundson Chair Professor. In 2007 he joined the faculty at the University of California, Santa Barbara. He has pioneered dissimilar materials epitaxial growth studies using a combination of molecular beam epitaxial growth with in-situ surface science probes including STM, XPS and AES, and ex-situ structural and electronic characterization. An important aspect of his work has been to go beyond surface science and structural studies to make materials for device structures allowing for detailed electrical and optical measurements of materials and interfacial properties. Specific studies have emphasized metallization of semiconductors, dissimilar materials epitaxial growth, thin film analysis, and molecular beam and chemical beam epitaxial growth of III-V semiconductor heterostructures, metallic compounds, metal oxides, multifunctional, magnetic, thermoelectric, and spintronic materials, and superconductors. He is the author of 300+ publications, including five review chapters and research monographs. In 2015 he received the North American MBE Innovator Award and was made a DOD National Security Science and Engineering Faculty Fellow (now called Vannevar Bush Faculty Fellowship) and in 2018 the APS Adler Award. He is Fellow of AVS, APS, and MRS.