Anisotropy, band-to-band transitions, phonon modes, and oxidation properties of cobalt-oxide core-shell slanted columnar thin films

Authors

Alyssa Mock, University of Nebraska-LincolnFollow
Rafał Korlacki, University of Nebraska-LincolnFollow
Chad Briley, University of Nebraska-LincolnFollow
Derek Sekora, University of Nebraska-LincolnFollow
Tino Hofmann, University of Nebraska-LincolnFollow
Peter M. Wilson, University of Nebraska–LincolnFollow
Alexander Sinitskii, University of Nebraska-LincolnFollow
Eva Schubert, University of Nebraska-LincolnFollow
Mathias Schubert, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2016

Citation

APPLIED PHYSICS LETTERS 108, 051905 (2016)

Comments

Copyright 2016 AIP Publishing LLC.

Abstract

Highly ordered and spatially coherent cobalt slanted columnar thin films (SCTFs) were deposited by glancing angle deposition onto silicon substrates, and subsequently oxidized by annealing at 475°C. Scanning electron microscopy, Raman scattering, generalized ellipsometry, and density functional theory investigations reveal shape-invariant transformation of the slanted nanocolumns from metallic to transparent metal-oxide core-shell structures with properties characteristic of spinel cobalt oxide. We find passivation of Co-SCTFs yielding Co-Al₂O₃core-shell structures produced by conformal deposition of a few nanometers of alumina using atomic layer deposition fully prevents cobalt oxidation in ambient and from annealing up to 475°C.