Emergent Phenomena at Flat Interfaces between Nitrides and Oxides

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This project is supported by the Electronic and Photonic Materials Program and by the Ceramics Program, both in the Division of Materials Research.Nontechnical Description: The NCSU (North Carolina State University) research team of Maria and Sitar explores the junction of nitride and oxide semiconductors with specific attention to the interfaces that bond them. When correctly prepared, these interfaces can host a high concentration of high-speed electrons that are confined to a two-dimensional layer. This new type of material is designed to have controllable electron density at the interface and opens new possibilities for future electronic devices. The research project involves graduate undergraduate students. The team disseminates the research findings through various educational outreach activities. For example, the annual NCSU Science and Mathematics Interactive Learning Experience (SMILE) camp engages middle-school and advanced fifth grade students to explore the principles of materials science in the PIs' research labs.Technical Description: The Maria and Sitar research team explores semiconductor-grade heteroepitaxial interfaces between complex oxides (e.g., MgO-CaO) and GaN. The properties and performance of these heterostructures are regulated by the electronic structure of the constituent crystals as opposed to unwanted defects, structural imperfections, or undesired chemical interactions. Seamless integration across two classes of materials is expected to create pathways to intimately couple their properties. To accomplish these goals, the team combines two advanced materials synthesis methods: surfactant-assisted film growth and confined epitaxy. Surfactant assisted growth overcomes the challenges of oxide faceting, while confined epitaxy creates step-free surfaces and thus perfectly flat interfaces. Using these approaches, the team is positioned to superimpose high room-temperature carrier mobility in compound semiconductors with nonlinear property responses of electronic oxides. This unique oxide/nitride heterostructure provides access to a new frontier of electronic, magnetic, optical, and interface physics.