10/29/19 - 9:45 AM to 11:00 AM
Department Seminar: Professor Joan M. Redwing
Heteroepitaxy in 2D: Challenges and New Approaches
The spectrum of two-dimensional (2D) materials “beyond graphene” has been continually expanding driven by the compelling properties of layered chalcogenide materials in monolayer and few-layer form. These materials include 2D transition metal dichalcogenide monolayer films that are only a few atoms thick, topological insulator bismuth chalcogenide films that only conduct on the 2D surface, and multilayers of dissimilar chalcogenide films whose properties are dominated by 2D interfaces. The full realization of the scientific and technological potential of 2D materials, however, will require developing atomic-level mastery over the wafer scale synthesis of samples with high crystalline quality and low defect densities.
Our research is aimed at the development of an epitaxial growth technology for layered chalcogenides similar to that which exists for III-V and other compound semiconductors, based on metalorganic chemical vapor deposition (MOCVD). Our studies have focused primarily on epitaxial growth of transition metal dichalcogenides including WSe2, MoS2 and WS2 and are aimed at understanding fundamentals of nucleation, epitaxy and anisotropic growth that are characteristic of van der Waals crystals. In this case, point defects and surface steps can be used to control the nucleation density and orientation of TMD domains as demonstrated for epitaxial growth on hBN and sapphire, respectively. The use of this approach for the fabrication of alloys and vertical/lateral TMD heterostructures will also be discussed.
Joan M. Redwing received her Bachelor of Science in chemical engineering from the University of Pittsburgh, and her doctorate in chemical engineering from the University of Wisconsin-Madison. After receiving her doctorate, she was employed as a research engineer at Advanced Technology Materials, where she worked on the development of group III-nitride materials and devices. Redwing joined the faculty of the Department of Materials Science and Engineering at Penn State University in 2000. She holds appointments in the Department of Electrical Engineering and the Department of Chemical Engineering, and is a member of the Materials Research Institute.
Redwing’s research interests are in the general area of electronic materials synthesis and characterization with a specific emphasis on semiconductor thin film, nanowire and 2D materials fabrication by chemical vapor deposition. She currently serves as secretary of the American Association for Crystal Growth and is an associate editor for the Journal of Crystal Growth and the Journal of Materials Research. She is a co-author of more than 250 publications and holds 8 U.S. patents.
Event DetailsLocation: 331 Smith HallHost: Professor James Johns