Rachel S. Goldman
Deparatment of Materials Science and Engineering
University of Michigan

Recently, nanostructures have shown significant promise for various applications in electronics, optoelectronics, and photonics. For example, nanometer-sized metallic droplets often form on compound semiconductor surfaces during epitaxial growth, thermal annealing, and/or ion irradiation. Such metal droplets may be used for the growth of quantum dots, via droplet epitaxy, or for nanowires, via the vapor-liquid-solid mode. For both cases, the nanostructure formation mechanisms are not well understood. Therefore, in this work, we have examined the formation of nanostructures during FIB irradiation of GaAs, GaSb, GaN, InAs, InP and InSb surfaces. On these semiconductor surfaces, randomly distributed group III rich droplets are observed to form at a critical dose. Subsequent ion beam irradiation leads to growth, motion, and coalescence of the droplets. On some surfaces, further irradiation leads to droplet motion; on other surfaces, nanowires are directly nucleated. We have examined the droplet formation mechanisms by introducing nucleation sites and effective diffusion lengths. Detailed nanostructure formation mechanisms based upon ion-enhanced surface diffusion and sputtering and/or sublimation will be discussed. In addition, strategies for fabrication of 3D nanocomposites will be presented.

This work is supported in part by AFOSR-MURI and ARO-DURIP.

Brief Biography: Rachel S. Goldman is Professor of Materials Science & Engineering, Electrical Engineering & Computer Science, and Physics at the University of Michigan (UM). During 2005-2006, she was the Augustus Anson Whitney Fellow at the Radcliffe Institute and Visiting Scientist in the Division of Engineering and Applied Sciences at Harvard University . Goldman received her B.S. in Physics (high honors with distinction) from UM. During the summers following her sophomore and senior years, Goldman interned at Brookhaven National Laboratory in Upton , NY and Thomson-CSF in Orsay , France . She then received her M.S. in Applied Physics from Cornell University and her PhD in Materials Science from the University of California , San Diego . Following her PhD, Goldman was a postdoctoral fellow at Carnegie Mellon University . In 1997, she joined UM as the Dow Corning Assistant Professor. Goldman's research interests are in the atomic-scale design of electronic materials, with a focus on the mechanisms of strain relaxation, alloy formation, and diffusion; and correlations between microstructure and electronic, magnetic, and optical properties of semiconductor films, nanostructures, and heterostructures. Goldman is the author of more than 60 publications, and she has delivered more than 120 invited talks. Goldman has received an MRS Graduate Student Award, an NSF CAREER Award, the AVS Peter Mark Memorial Award, and the UM Ted Kennedy Family Team Award. She has organized 2 MRS Symposia and 3 APS Focus Sessions, served on the MRS Publications Committee, and served as Chair of the EMPD Division of AVS. Goldman is currently Associate Editor of Journal of Electronic Materials , and Volume Organizer for the MRS Bulletin . She is also serving 3­year terms as a member of the AVS Trustee, an APS-FIAP Member-at-Large, and a member of the TMS/IEEE Electronic Materials Committee.

For further information please contact Prof. Donald Morelli, Department of Chemical Engineering and Materials Science at dmorell@egr.msu.edu

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