BYU

Abstract by Nick Allen

Personal Infomation


Presenter's Name

Nick Allen

Degree Level

Doctorate

Co-Authors

Dhruv Shah
Richard Vanfleet
Matthew Linford
Robert Davis

Abstract Infomation


Department

Physics and Astronomy

Faculty Advisor

Robert Davis

Title

Optical constants and thickness of ultrathin thermally evaporated iron films.

Abstract

Carbon nanotube templated microfabrication (CNT-M) is a technique that uses a patterned iron catalyst to grow 3-D structures for device applications. Iron catalyst thickness strongly affects carbon nanotube (CNT) growth heights and the straightness of the CNT-M structures. Atomic force microscopy (AFM) has been used to directly measure the thicknesses of such iron/iron oxide films, but this technique is slow and not easily scalable. A faster method is ellipsometry, but for very thin films, the optical constants and thickness are not easily separated, thus standard ellipsometry approaches are inadequate. The 2-10 nm thick iron films used as CNT growth catalysts are in this challenging region. The absorptive nature of the iron/iron oxide films adds further difficulty. In this study, a multi-sample ellipsometry analysis using iron films of various thicknesses was performed to obtain the optical constants of thermally evaporated iron. We used contrast enhancement by incorporating a silicon dioxide layer under the film being analyzed to enhance sensitivity to the optical constants. Iron thicknesses were verified by AFM, and the two methods mostly agreed.