This project is jointly funded by the Electronic and Photonic Materials (EPM) Program in the Division of Materials Research (DMR) and the Electronics, Photonics, and Magnetic Devices (EPMD) Program in the Division of Electrical, Communications and Cyber Systems (ECCS).
This research project studies hybrid graphene-ferroelectric materials and devices. The hybrid materials offer promise for combining the strength of the unique two-dimensional Dirac Fermionic electronic structure and high carrier mobility in graphene plus the high functionality in ferroelectric materials. The research is designed to overcome undesirable polarization screening by absorbates on the surface of ferroelectric materials by the use of artificially layered superlattice materials in the form of epitaxial thin films, in which the phase transition temperature and dielectric response of the material can be precisely tailored. The research focuses mainly on two aspects: (1). A ferroelectric material is used to charge dope a graphene sheet in contact with it to a much higher extent than the conventional dielectrics can. Based on the principle of ferroelectric charge doping, atomic force microscopy are used for "on-demand" fabrication of nano-junctions and circuits, allowing definition of sharp potential profiles with arbitrary designs, enabling exploration of the physics of Dirac electron scattering through both scanning probe imaging and electrical transport measurements. (2). A ferroelectric material is used to exert precisely controlled strain on a graphene sheet in particular directions to modify the electronic properties and to study the theoretically predicted gauge field effects.
The project addresses basic and applied research issues in an interdisciplinary area that combines physics, materials science and device engineering, with high technological relevance. The unique properties of graphene are exploited in new device structures that utilize both the ferroelectric field effect and piezoelectric strain. Prototype devices studied in the project could form the seed for next-generation electronics such as novel transistors with low-power consumption and high mobility, non-volatile memory devices, and devices based on strained graphene. Graduate students, as well as undergraduate and high-school students, are trained in an interdisciplinary environment and learn thin-film deposition, lithography, atomic force microscopy, and electrical characterization.