Date: Monday, Apr 16th
Presenter: Prof. Patrick Lenahan, Penn State University
Silicon Carbide based devices have great promise in high power and high temperature applications. Unfortunately, the development of SiC based devices has been hampered by the presence of as yet poorly understood trapping defects. In collaboration with researchers at several industrial and government R and D centers, we have developed a partial understanding of the physical and chemical nature of these traps through a combination of electrically detected magnetic resonance (EDMR) and conventional electronic measurements. The major focus of our work has been on SiC MOSFETs, with more limited emphasis on SiC based bipolar junction transistors, JFETs, and simple pn junctions. EDMR involves the observation of electronic defects in fully processed semiconductor devices via changes in device current caused by magnetic resonance induced electron spin flipping at the defects. The EDMR measurements can provide both a fairly detailed physical description of the defects and some information regarding energy levels and physical location. The presentation will include a brief discussion of spin dependent gated diode current (DCIVC) measurements, spin dependent charge pumping, and observation of EDMR through spin dependent tunneling. Since these techniques are not widely utilized in solid state electronics at the present time, and since these techniques may be applicable to many other topics of current interest, the presentation will include an introduction to EDMR and magnetic resonance in semiconductors.
Patrick Lenahan earned a B.S. degree from the University of Notre Dame and a Ph.D. from the University of Illinois, Champaign-Urbana. After completing his Ph.D. in 1979, he was a post-doctoral fellow at Princeton University in 1979 and 1980. From 1980 until 1985 he was a member of the technical staff in the Materials Research Directorate of Sandia National Laboratories in Albuquerque, New Mexico. Since 1985 he has been at Penn State University where he is Distinguished Professor of Engineering Science and Mechanics (ESM) and Co-Chair of the Inter-College Program in Materials. The Inter-College Program in Materials is Penn States interdisciplinary graduate program in Materials Science and Engineering. In 2001, he was visiting professor of Electronics and Computer Engineering at Nihon University, Tokyo, Japan. From 2000 to 2004, he served as associate editor of the Journal of Electronic Materials.
Dr. Lenahan has authored over 175 publications, approximately 135 in refereed journals, approximately 300 conference presentations, and one patent. The work has been cited about 4000 times in the scientific and technical literature. He is a fellow of the IEEE.