ELECTRICAL/DIELECTRIC PROPERTIES OF METAL-OXIDE NANOFILMS VIA ANODIZING AL/HF METAL LAYERS

1 BENDOVA Maria
Co-authors:
1 MOZALEV Alexander
Institution:
1 CEITEC – Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic, alexander.mozalev@ceitec.vutbr.cz
Conference:
9th International Conference on Nanomaterials - Research & Application, Hotel Voronez I, Brno, Czech Republic, EU, October 18th - 20th 2017
Proceedings:
Proceedings 9th International Conference on Nanomaterials - Research & Application
Pages:
51-56
ISBN:
978-80-87294-81-9
ISSN:
2694-930X
Published:
8th March 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
140 views / 71 downloads
Abstract

Hafnium oxide (HfO2) is a high-temperature ceramic with excellent electrical, dielectric and optical properties, which may be substantially enhanced in the nanostructured material. Here, we have developed self-organized arrays of hafnium-oxide nanorods and examined their properties by electrochemical impedance spectroscopy (EIS). For sample preparation, Al/Hf layers are magnetron sputtered onto SiO2/Si substrates, anodized and then re-anodized to a more anodic potential. This results in the growth of a porous alumina film, followed by pore-assisted oxidation of the Hf underlayer. The films consist of discrete HfOx protrusions, penetrating the alumina pores and anchored to a uniform oxide layer that forms under the pores. Post-anodizing treatments include annealing at 600°C in air or vacuum and selective dissolution of the alumina overlayer. The electrical/dielectric behavior of the hafnium oxide nanorod arrays, embedded in or free from alumina, was EIS-investigated in a borate buffer solution. In the re-anodized (not annealed) state the bottom oxide layer behaves as a good dielectric whereas the nanorods are semiconducting in nature. This situation does not change substantially by the annealing in air, still resulting in a dielectric bottom layer and semiconducting nanorods. However, after the annealing in vacuum, the whole film becomes an n-type semiconductor. Further investigation is in progress to understand the formation-structure-morphology relationship, aiming at exploring the functional properties of the films.

Keywords: porous anodic alumina, anodizing, nanostructured hafnium oxide, dielectric, semiconductor

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