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Insulator-Metal Transition in Nanostructured Ni-Al Thin Films

Published online by Cambridge University Press:  21 February 2011

H.P. Ng  and
A.H.W. Ngan
H.P. Ng
Affiliation:
Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, R China.
A.H.W. Ngan
Affiliation:
Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, R China.
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Abstract

The electrical resistance of Ni-Al alloy thin films prepared by dc magnetron sputtering process was found to be abnormally high at room temperature. However, when heated at elevated temperatures, the resistance dropped significantly, exhibiting a remarkable negative temperature coefficient of resistance (TCR). The phenomenon was found to be substrate-independent. Cross-sectional transmission electron microscopy revealed that the films were essentially nanocrystalline and porous in nature. Analysis of the current density-electric field characteristics yielded a satisfactory agreement with either the space charge limited or the Poole-Frenkel models for electrical conduction. The negative TCR effect diminishes and the usual metallic resistance is restored in thicker films, probably due to reduction in particle separation and further coalescence of neighbouring crystallites.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 581: Symposium F – Nanophase & Nanocomposite Materials II , 1999 , 571
Copyright
Copyright © Materials Research Society 2000

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References

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