Stanford Mechanics and Computation
Home
People
Research
Teaching
Seminar Schedule
FAQ
for
Elasticity, Fracture and Piezoelectricity Size Effects in Semiconducting Nanowires
=Horacio Espinosa, Ph.D.= ===April 7, 2011=== Elasticity, Fracture and Piezoelectricity Size Effects in Semiconducting Nanowires In recent years there has been a major thrust to develop novel nanomaterials, e.g., semiconducting nanowires (NWs), exhibiting unique electro-mechanical properties. These nanostructures are envisioned as building blocks for the next generation of electronic devices, biosensors for proteomics screening, waveguides, and energy harvesting systems. In this context, identification of scale dependent properties is essential. However, such endeavor has proven challenging from both experimental and modeling perspectives. In this seminar, a MEMS-based nanoscale material testing system designed to serve as a platform for in-situ electron microscopy testing of one dimensional (1-D) nanostructures will be introduced and used to identify mechanical property size effects in ZnO and GaN nanowires. The validity of force fields commonly used to model these semiconducting materials will be discussed by comparison to experimental findings and quantum mechanical simulations. It will be shown that force fields are accurate enough to capture elasticity size effects but that higher order theories are needed to interpret nanowire failure. Furthermore, while both ZnO and GaN possess the same wurtzite crystal structure, they exhibit quite different elastic and piezoelectric size dependences. The seminar will close with a discussion of opportunities arising from such size effects in energy harvesting applications. About the speaker: Horacio D. Espinosa is the James and Nancy Farley Professor of Mechanical Engineering at Northwestern University. He received his Ph.D. in Applied Mechanics from Brown University, in 1992. He has made contributions in the areas of dynamic failure of advanced materials, micro and nanomechanics. He has published over 200 technical papers in these fields. Professor Espinosa has received numerous awards and honors including two Young Investigator Awards, NSF-Career and ONR-YIP, and the American Academy of Mechanics (AAM) and Society of Engineering Science Junior Medals. He also received the Society for Experimental Mechanics 2005 Hetenyi and 2008 Lazan Awards. He is a member of the European Academy of Arts and Sciences, and Fellow of AAM, ASME, and SEM. He served as Editor-in-chief of the Journal of Experimental Mechanics and Associate Editor of the Journal of Applied Mechanics. Currently, he is a co-editor of the Wiley Book Series in Micro and Nanotechnologies and serves in several journal editorial boards.
Return to
Elasticity, Fracture and Piezoelectricity Size Effects in Semiconducting Nanowires
.