"Variation of Grain Size in Niobium Thin Films"
Benjamin Rich, Advisor: Dr. Joseph C. Amato
The goal of my project ws to deposit thin films of niobium (Nb) with controlled grain size, and
to measure that grain size using x-ray diffractometry and atomic force microscopy. Nb is a type
II superconductor, which means that it has a mixed state that supports magnetic vortices when
exposed to a magnetic field. Sputtered thin films are composed of tiny crystal grains, and
vortices tend to get pinned to grain boundaries. By applying a dc voltage bias to the sample, I can
control the grain size. The width of the x-ray Bragg peaks is used to determine the grain size
using the Scherrer equation. the overall goal of my project is to find a preparation technique
which will produce films with low intrinsic pinning, so that added synthetic pinning sites will
provide the dominant pinning forces in the film.