报告题目：Role of Excited States in Recombination Processes
报 告 人：Chris G. Van de Walle
Herbert Kroemer Distinguished Professor of Materials
University of California, Santa Barbara
Member of the National Academy of Engineering, USA
Point defects can strongly impact the performance of semiconductor devices; they may act as compensating centers, charge traps, or recombination centers. Defect-assisted recombination, also known as Shockley-Read-Hall recombination, degrades the performance of electronic and optoelectronic devices. Point defects can also be used beneficially, for instance in quantum information science as analogs of the NV center in diamond. I will discuss the theoretical advances that are enabling us to calculate energetics as well as electronic and optical properties with unprecedented accuracy. In addition to radiative recombination, we also study nonradiative processes. Based on simple rules, one expects defect-assisted nonradiative recombination to become less important in wider-gap materials, but a number of examples show a different trend. We have explained this by noting the crucial role of excited states in recombination processes, transition-metal impurities being an important example.
Chris Van de Walle is a Distinguished Professor of Materials at the University of California, Santa Barbara and holds the Herbert Kroemer Endowed Chair in Materials Science. 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 postdoctoral scientist at IBM Yorktown Heights (1986-1988) and a Senior Member of Research Staff at Philips Laboratories in Briarcliff Manor (1988-1991). He has published over 350 research papers, holds 23 patents, and has given over 180 invited and plenary talks at international conferences. Van de Walle is a Member of the National Academy of Engineering, a Fellow of the APS, AVS, AAAS, MRS, and IEEE, as well as 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.