Special Seminar - Oct. 27th at 3:00pm in MRGN 206 Rachel S. Goldman University of Michigan Title: Ion-Induced Nanostructure Formation on Compound Semiconductor Surfaces Abstract: Ion-irradiation of semiconductor surfaces has emerged as a promising approach to generate a variety of self-organized nanostructures, ranging from islands to ripples to nanorods. We have examined ion-induced transformations for a wide variety of focused-ion-beam (FIB) irradiated III-V compound semiconductor surfaces. On Ga-V and In-V surfaces, FIB-irradiation beyond a threshold ion dose leads to the formation of Ga-rich droplets [1] and In-rich islands, respectively. Interestingly, the threshold ion dose increases with increasing surface binding energy, suggesting a key role of sputtering on nanostructure formation. For low binding energy compounds, the surface morphology evolves from pits to ripples, followed by the nucleation of islands on the ripple crests, and the subsequent formation of nanorods. Together, these results suggest a nanostructure formation mechanism based upon ion-induced non-erosive surface response, followed by preferential Group V sputtering and island-induced self-shielding. In this talk, I will discuss our investigations of nanostructure array formation on a wide variety of III-V surfaces, with a focus on the formation mechanisms and electronic and optical properties of InSb nanorods and Ga nanodroplets. I will also discuss progress towards the design and fabrication of 3D Ga nanodroplet arrays. Brief Bio: Rachel S. Goldman is a professor of MSE, Physics, and EECS at UM. She received degrees from UM (B.S. Physics, 1988), Cornell (M.S. Applied Physics, 1992), and UC-San Diego (PhD Materials Science, 1995). Following her PhD, she was a postdoctoral fellow in Physics at Carnegie Mellon University. In 1997, she joined the UM faculty as the Dow Corning Assistant Professor. She received the Peter Mark Memorial Award from the AVS in 2002, the Ted Kennedy Family Team Award from UM in 2004, the Augustus Anson Whitney Fellowship from the Radcliffe Institute in 2005, and the Monroe-Brown Foundation Service Excellence Award from UM in 2011. She currently serves as Graduate Chair for MSE, Associate Director of Applied Physics, Associate Director of the DoE Center for Solar and Thermal Energy Conversion, and Associate Director for Education and Outreach of the NSF Materials Research Science and Engineering Center at UM. She has held editorial positions for the Bulletin of the Materials Research Society, the Journal of Electronic Materials, the Journal of Vacuum Science and Technology, and Thin Solid Films. Goldman is currently a Trustee of the AVS. In addition, she has served on the AVS Board of Directors (2005-2008) and is active in committee leadership and symposium organization for MRS, TMS, and APS. Jaime Turner Birck Nanotechnology Center Purdue University 1205 West State STreet West Lafayette, IN 47907-2057 (765) 494-3509 jjturner@purdue.edu