Events

 
Seminar
Nano Structured GaN/GaAlN Field Effect Transistors

by Professor Manfred Pilkuhn, University of Stuttgart, Germany.

Date
 :  13 May 2005 (Fri)
Time
 :  4:00pm - 5:00pm
Venue  :  Room 3401, 3/F (Lifts 17-18) , HKUST

Abstract
III-V nitrides are interesting materials for high mobility field effect transistors (HEMTs). High quality epitaxial layers of GaN, GaAlN, and GaInN have been grown by vapor phase epitaxy with metalorganic compounds (MOVPE). The characterization of these films by low temperature photoluminescence and by x-ray diffraction will be described. A two dimensional electron gas can form at the interface of GaN/GaAlN heterojunctions due to piezoelectric and polarization induced charges, and its electrical properties were investigated including de Haas- Shubnikov oscillations. Ultrashort channel HEMTs (L<50 nm) with T-shaped gates have excellent high frequency performance (ft> 70 GHz, fmax>150 GHz). A recess gate technology was developed. Transconductance (>250 mS/mm), threshold voltage, breakdown voltage, etc., were studied as a function of gate length. High temperature performance up to about 400 C was demonstrated.


Biography
University education: Braunschweig University (Germany), Dublin University/Trinity College (Ireland). Degrees: Diplom -degree (Physics, 1957), Dr.rer.nat. (Applied Physics, 1960), Dr. habil. (Electrical Engineering, 1966). Staff member at the IBM Research Center (New York, 1961-1966) with early work on LED's and semiconductor lasers. Associate professor at Frankfurt University (Germany) 1967 to 1969. Since 1969, chair professor and director of the Physics Institute at Stuttgart University (Germany). Dean of the Physics Faculty for 4 terms. Research on semiconductor device physics, optoelectronics (mainly semiconductor lasers), FET's. Materials research mainly on III-V compounds (GaAs, InP, GaN, GaSb, etc.), and Si. Molecular electronics, organic FET's. Since 2002, Professor Emeritus (Stuttgart University). Member of the Academy of Science (Mainz, Germany). Honorary professor at National Chiao Tung University (Taiwan), consulting professor at Tongji University Shanghai., and co-founder of the Pohl -Institute on dielectrics. Guest professor at Tokyo Institute of Technology, University of California Santa Barbara (UCSB), Dublin University, Cheng Kung University (Taiwan), and others. Presently visiting professor at Hong Kong Polytechnic University.

 

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