Structural and optical properties of cobalt slanted nanopillars conformally coated with few-layer graphene

Authors

Peter M. Wilson, University of Nebraska—LincolnFollow
Alexey Lipatov, University of Nebraska-LincolnFollow
Daniel Schmidt, University of Nebraska—Lincoln
Eva Schubert, University of Nebraska—LincolnFollow
Mathias Schubert, University of Nebraska—LincolnFollow
Alexander Sinitskii, University of Nebraska-LincolnFollow
Tino Hofmann, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2015

Citation

APPLIED PHYSICS LETTERS 106, 231901 (2015)

Comments

Copyright 2015 AIP Publishing LLC.

Abstract

Optical characterization of anisotropic multicomponent nanostructures is generally not a trivial task, since the relation between a material’s structural properties and its permittivity tensor is nonlinear. In this regard, an array of slanted cobalt nanopillars that are conformally coated with few-layer graphene is a particularly challenging object for optical characterization, as it has a complex anisotropic geometry and comprises several materials with different topologies and filling fractions. Normally, a detailed characterization of such complex nanostructures would require a combination of several microscopic and spectroscopic techniques. In this letter, we demonstrate that the important structural parameters of these graphene-coated sculptured thin films can be determined using a fast and simple generalized spectroscopic ellipsometry test combined with an anisotropic Bruggeman effective medium approximation. The graphene coverage as well as structural parameters of nanostructured thin films agree excellently with electron microscopy and Raman spectroscopy observations. The demonstrated optical approach may also be applied to the characterization of other nanostructured materials.