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INSTITUTE OF ELECTRICAL AND ELECTRONIC ENGINEERS WAVES AND DEVICES PHOENIX CHAPTER February 22, 2006 EDS Meeting www.eas.asu.edu/~wadweb III-Nitride Heterojunction Field Effect Transistors Prof. Lester F. Eastman Cornell University ECE and CNF Abstract The physical basis, technology and performance of AlGaN/GaN FET’s with their undoped polarizationinduced, two-dimensional-electron-gases (2DEG’s) will be presented. The unique properties of the Wurtzite heterojunction crystals involved include 1x1013/cm2 electron sheet density, 3 megavolt/cm electric field strength, and the electron transit velocity up to 1x10 7 cm/s. Means of making ohmic contact to the 2DEG’s as well as the the Schottky barrier gate to control the drain current, and the Si 3N4 passivation of the exposed semiconductor surface to stabilize its charge will be included. Using simple mushroom-shaped-cross-section gates, power levels to >11W/mm, and 10W for 1.5mm periphery will be shown. The limits of Al composition and thickness of the strained, pseudomorphic AlGaN barrier are included, and layered structures are presented. The Ni/Au gate metal cross-section shape will be explained, as the means of obtaining 120 Ω/mm gate resistance for 0.25 μm gates. The experimental and analytical aspects of the layout pattern, and its impact on power-added efficiency will be explained. The short-fall of electron transit velocity, from its prediction based on Monte Carlo simulations, will be explained in terms of a pile-up of longitudinal optical phonons in the channel. Velocity overshoot measurements by Dr. Michael Wrabach will be reviewed and explained. A comparison of similar effects in SiC MESFET’s will also be made. A plan for using doped channels, to limit the electron density will be presented. Finally, the figure of merit of GaN, SiC and metamorphic GaAs structures will be compared. Biography Lester F. Eastman joined the faculty of Electrical Engineering at Cornell in 1957, and also serves as a member of the graduate fields of Applied Physics and Materials Science. Since 1965, he has been doing research on compound semiconductor materials, high speed devices, and circuits, and has been active in organizing workshops and conferences on these subjects elsewhere since 1965 and at Cornell from 1967. In 1977, he joined other Cornell faculty members in obtaining funding and founding the National Research and Resource Facility for Submicron Structures at Cornell (now Cornell Nanofabrication Facility). Also in 1977, he founded the Joint Services Electronics Program and directed it until 1987. He has supervised 120 Ph.D. theses, over 50 M.S. theses, and over 50 post-doctoral studies. In his research group, effort is underway on III-nitride molecular beam epitaxy, microwave transistors, and fundamental phenomena. He was a member of the U.S. Government Advisory Group on Electron Devices from 1978-1988, and has served as a consultant for several industries. From 1987-1993 he served as a member of the Kuratorium (Visiting Senior Advisory Board) of the Fraunhofer Applied Physics Institute in Freiburg, Germany. He has been a Fellow of IEEE since 1969, a member of the National Academy of Engineering since 1986, and has been appointed the John L. Given Foundation Chair Professor of Engineering at Cornell in January 1985. The IEEE honored him with their 1999 Graduate Teaching Award and the 2000 Third Millennium Medal. In 2001, he was made Fellow of the American Physical Society. He is the recipient of the 2002 J.J. Ebers Award of the IEEE Electron Device Society. In 2002, the IEEE “Lester Eastman Conference” on High Performance Devices, to be held biannually, was established. Date: February 22, 2006 Location: Bernoulli Conference Rm, Bldg 99, Freescale Semiconductor, 2100 E. Elliot Rd., Tempe, AZ Drive North on Country Club off Elliot on the western edge of the Freescale site, enter back parking lot Time: 3:30 - 4:30 pm Presentation For more information, please call Chuck Weitzel (Chapter Chair) at (480) 413-5906.