Connecting Layered Materials to Semiconductors: The Ubiquity of Schottky Barriers and Tunnel Junctions
Abstract Details: It is widely recognized that interfaces between metals and most semiconductors form Schottky barriers with rectifying properties that are essential components of present-day electronics. This talk will begin with a tutorial overview of Schottky barriers and describe the physical concepts that are necessary and sufficient to gain a working understanding of their operation. Research will then be described which uncovers surprising phenomenology that points to new physics and novel device concepts. These phenomena include magnetodielectric coupling in nonmagnetic Au/GaAs:Si Schottky barriers, the formation of Schottky barriers at the interface of one-atom-thick zero-gap semiconductors (graphene), and the Schottky barriers formed by contacting freshly exfoliated flakes of van der Waals crystals such as Bi2Se3 (a topological insulator), layered transition metal dichalcogenides (such as TaS2, TiSe2 and NbSe2) harboring charge density waves and freshly cleaved Bi-2212 (a high Tc cuprate superconductor) to doped Si and GaAs wafers. Interestingly, modifications to the thermionic emission equation provide an excellent description of current-voltage characteristics at low temperatures where tunneling is known to be important, thereby providing a segue to a full tunneling description. Temperature, frequency and magnetic field dependence of current-voltage and capacitance-voltage characteristics will be described.Â
About The Speaker: Arthur Foster Hebard is a Distinguished Professor of Physics at University of Florida in Gainesville, Florida. He is particularly noted for leading the discovery of superconductivity in Buckminsterfullerene in 1991. Art Hebard attended The Hotchkiss School and graduated with a BA in Physics from Yale University in 1962. He obtained his PhD from Stanford University in 1971 under William M. Fairbank with thesis Search for fractional charge using low temperature techniques. After a spell as a Research Associate at Stanford, he became a member of the Technical Staff at AT&T Bell Telephone Laboratories. He moved to the University of Florida as a Professor in 1996, and in 2007 was given the title of Distinguished Professor. He is the author of more than 250 refereed scientific publications and 90 invited presentations, and has been issued 10 patents. He was awarded the 2008Â James C. McGroddy Prize for New Materials by the American Physical Society, and a co-recipient of the 2015 Oliver E. Buckley Condensed Matter Prize, also given by the American Physical Society, 'For discovery and pioneering investigations of the superconductor-insulator transition, a paradigm for quantum phase transitions.' His research interests include thin-film physics, graphene, fullerenes and fullerene derived compounds, superconductivity, dilute magnetic semiconductors, magnetism in thin films and at thin film interfaces, interface capacitance, magnetocapacitance of complex oxides and semiconductors. Notable recent work has been on the use of graphene for solar cells."
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