Colloquium: Prof. Nuri Öncel
Friday Feb 20, 2015, 4:00–5:00pm, 211 Witmer Hall. Refreshments at 3:30pm in 215 Witmer Hall.
Iridium-Modified Silicon Surfaces
Dr. Nuri Öncel
Dept. of Physics & Astrophysics
University of North Dakota
Although there is an extensive literature for almost all metal/silicon systems, the early stages of iridium (Ir) growth on various silicon (Si) surfaces have not been studied in detail. In order to explore the physical and electronic properties of these interfaces; we have performed a detailed study of Ir modified Si(001) (Ir/Si(001)) and Si(111) (Ir/Si(111)) surfaces. Ir/Si(111) surface hosts Ir-ring clusters. The clusters are made out of one Ir atom surrounded by six silicon atoms. We studied this interface with the help of Scanning Tunneling Microscopy/Spectroscopy (STM/STS), Angle Resolved Photoemission Spectroscopy (ARPES) and Density Functional Theory (DFT). On the other hand, Ir/Si(001) surface exhibits p(2×2) domains on LEED intensity images. The STM images show that the basis of the crystal lattice consists of an Ir atom and a Si dimer and similar to Si(001) dimer rows, they are aligned parallel to the orthogonal  directions.