Using the right criteria for design and discovery
Event details
| Date | 21.09.2017 |
| Hour | 16:15 › 17:15 |
| Speaker |
Prof. Chris G. Van De Walle, University of California, Santa Barbara, USA Bio: Ph. D. E. E., Stanford University, 1986. Postdoctoral Scientist, IBM T. J. Watson Research Center, Yorktown Heights, New York (1986-1988). Senior Member of Research Staff, Philips Laboratories, Briarcliff Manor, New York (1988-1991). Adjunct Professor, Columbia University, New York (1991). Principal Scientist/Senior Member/Member of Research Staff, Xerox Palo Alto Research Center (PARC), Palo Alto, California (1991-2004 ). Alexander von Humboldt US Senior Scientist at the Fritz-Haber-Institut and the Paul-Drude-Institut, Berlin, Germany (May-October 1999). Professor, Materials Department, University of California, Santa Barbara (2004-). Herbert Kroemer Chair in Materials Science, University of California, Santa Barbara (2013-). Distinguished Professor, Materials Department, University of California, Santa Barbara (2015-). |
| Location | |
| Category | Conferences - Seminars |
Materials design and discovery require a thorough knowledge of the underlying physics. Incomplete understanding can lead to misguided searches, both experimentally and computationally. I will illustrate these points with two case studies.
The Mott-Hubbard gaps of rare-earth titanates are commonly reported to be 0.2-0.7 eV. These values are based on optical reflectivity measurements, from which the onset of optical absorption is derived. Rigorous computational and experimental studies for GdTiO3 indicate that the gap is significantly larger, and that the previously identified feature in the optical absorption is due to the excitation of small hole polarons. These findings likely apply to a broader set of materials, and impact the design of complex-oxide heterostructures as well as the search for materials in which the metal-insulator transition can be exploited.
Defect-assisted nonradiative recombination can severely affect the efficiency of electronic and optoelectronic devices. The rule of thumb for assessing whether a defect will lead to strong nonradiative recombination has been based on whether the defect level is close to mid-gap. However, we have found that strong nonradiative recombination can occur for defects that fail to meet this criterion. These insights also impact the search for novel qubits or single photon emitters for quantum information science.
13th NCCR MARVEL "Distinguished Lecture"
NCCR MARVEL - Events
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