Seminars

Chris Van de Walle
University of California, Santa Barbara

Hydrogen Interactions with Materials: From Transistors to Fuel Cells
Hydrogen is almost always unintentionally present as an impurity in materials, and often significantly affects their properties: structural materials are weakened by hydrogen embrittlement, semiconductors suffer a hydrogen-induced decrease in conductivity, and battery electrodes can degrade when exposed to hydrogen.  The application of hydrogen as an energy source in fuel cells lends additional urgency to understanding hydrogen interactions with materials.  First-principles calculations have allowed us to elucidate the many facets of this behavior.  A systematic study of hydrogen in a wide range of hosts has revealed the existence of a universal alignment for the electronic level of hydrogen in semiconductors, insulators, and even aqueous solutions.  The alignment allows predicting the electrical activity of hydrogen in any host material, and shows that the physics of hydrogen turns out to be unexpectedly connected to other important problems in materials physics and electrochemistry.

About Dr. Van de Walle:
Chris Van de Walle is a Distinguished Professor of Materials and the inaugural recipient of the Herbert Kroemer Endowed Chair in Materials Science at the University of California, Santa Barbara.  Prior to joining UCSB in 2004, he was a Principal Scientist at the Xerox Palo Alto Research Center (PARC).  He received his Ph.D. in Electrical Engineering from Stanford University in 1986, and was a postdoc at IBM Yorktown Heights (1986-1988) and a Senior Member of Research Staff at Philips Laboratories in Briarcliff Manor (1988-1991). Professor Van de Walle develops and employs first-principles computational techniques to model the structure and behavior of materials. He performs studies of interfaces, surfaces, defects and impurities, and has worked on wide-band-gap semiconductors, nitrides, oxides, hydrogen interactions with materials, and spin centers for quantum information science.  He has published over 400 research papers and holds 24 patents.  Van de Walle is a Member of the U. S. National Academy of Engineering, and the recipient of a Humboldt Award for Senior US Scientist, the David Adler Award from the APS, the Medard W. Welch Award from the AVS, and the TMS John Bardeen Award.