First principles modeling of oxides and their heterostructures

Complex oxide heterostructures have been intensively investigated in recent years. However, the widely used transition-metal oxides suffer from low carrier mobility, which limits device applications. For applications in electronics, the focus has shifted to materials such as BaSnO₃ and Ga₂O₃. They have large band gaps, rendering them suitable for transparent conductors and for high-frequency and power electronics, but can be highly n-type doped and exhibit good transport properties. Better control of dopants and point defects is still needed in order to improve materials quality and enable further applications. I will show how cutting-edge first-principles modeling, using hybrid functional calculations within density functional theory, can shed light on the multiple aspects of this problem: Band alignment and confinement of two-dimensional electron gases, carrier scattering and mobility, doping, point defects and their impact on carrier concentrations, energetics and electronic structure of alloys, and optical properties.

Bio: 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). He has published over 400 research papers, holds 24 patents and has given over 200 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.