Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1672507 | Thin Solid Films | 2009 | 6 Pages |
Abstract
The present work demonstrates the formation of porous niobium films with separated columnar structures by oblique angle magnetron sputtering for capacitor application. The niobium films deposited on textured aluminium substrates, which had concave cell structures with the cell sizes ranging from 125Â nm to 550Â nm, consist of isolated columns of niobium with wider gaps between columns developing on the substrates with larger cell sizes. The surface areas of the deposited films, evaluated by the capacitance of the anodic films formed at several voltages, increased with an increase in the cell size of substrate. The surface area decreases with an increase in the formation potential of anodic films from 2Â V to 10Â V vs Ag/AgCl, because the gaps are filled with anodic oxide as a consequence of the large Pilling-Bedworth ratio of 2.6 for the Nb/Nb2O5 system. The reduction of the surface area is suppressed when the substrate with larger cell size is used, due to the formation of niobium columns with wider gaps, which are not filled with anodic oxide. The high surface area even at higher formation voltages of the anodic films is a requisite for capacitor application.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Nanotechnology
Authors
M. Tauseef Tanvir, Y. Aoki, H. Habazaki,