MSE Fall Seminar Series 2022: Speaker Professor Daniel Gall

Description

Materials Property Guessing:

The Resistivity Problem

Daniel Gall

Rensselaer Polytechnic Institute

http://www.rpi.edu/~galld

Abstract: We can guess materials properties like the density or the melting point, but we (or at least I) fail completely in guessing the electrical resistivity of even of the simplest metals. In this talk, I will present the challenge of predicting the resistivity of metals, particularly for the case of narrow (~10 nm) wires where electron scattering at surfaces and grain boundaries dominate. We use vacuum deposition techniques to grow epitaxial Cu, Ag, Ta, Ti, Co, Ni, W, Mo, Rh, Ir layers to study electron scattering at surfaces and interfaces using in situ transport measurements. For example, electrons reflect from atomically smooth Cu(001) or Co(0001) surfaces like from a mirror, but when adding a sub-monolayer of Ti or exposing the surfaces to oxygen, the resistivity increases due to diffuse electron surface scattering. The resistivity increases at reduced dimensions. This is a major technological problem as this resistivity bottleneck limits the speed of interconnect lines in integrated circuits. New conducting materials are explored, including anisotropic conductors, intermetallics, layered carbides and nitrides. Their evaluation is challenging not only because of their more complex synthesis schemes but also because current semiclassical transport models completely fail in explaining their resistivity scaling. That is, we require both new conductive materials and a new model to describe their resistivity.

DANIEL GALL holds a professor position in Materials Science and Engineering at the Rensselaer Polytechnic Institute. He received his Ph.D. in physics from the University of Illinois at Urbana-Champaign in 2000. Prof. Gall’s research focuses on the development of an atomistic understanding of thin film growth and on the electronic and optical properties of materials. He is a Fellow of the American Vacuum Society and has won numerous awards from NSF, DoE, ASM International, RPI, IBM, ICMCTF and LAM for his work on transition metal nitrides and on high-conductivity interconnects. Professor Gall has authored over 180 peer-reviewed journal articles. His students won over 50 best poster and paper awards. http://www.rpi.edu/~galld