Rawal, Ishpal and Panwar, O. S. and Tripathi, R. K. and Singh, Avanish Pratap and Dhawan, S. K. and Srivastava, A. K. (2015) Effect of helium gas pressure on dc conduction mechanism and EMI shielding properties of nanocrystalline carbon thin films. Materials Chemistry and Physics, 158. pp. 10-17. ISSN 0254-0584

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Abstract

This paper reports the effect of helium partial pressures similar to 1.2 x 10(-5) (base pressure), 1.4 x 10(-4), 8.6 x 10(-3) and 0.1 mbar on the variable range hopping conduction in nanocrystalline carbon thin films deposited by filtered cathodic jet carbon arc technique. High resolution transmission electron microscopy studies suggest the random distribution of nanocrystallites (similar to 3-7 nm) in the amorphous matrix. The DC conduction behavior of the deposited nanocrystalline films has been studied in the light of Mott's variable range hopping (VRH) model and found to obey three dimensional VRH conduction. The randomly distributed nanocrystallites in amorphous matrix may lead to change in the distribution of density of states near Fermi level and hence, the conduction behavior. The enhanced electrical conductivity of the deposited films due to the helium environment makes them suitable for electromagnetic interference shielding applications. The sample deposited at a helium partial pressure of 0.1 mbar has a value of shielding effectiveness similar to 7.84 dB at 18 GHz frequency.

Item Type:	Article
Uncontrolled Keywords:	Nanostructures Thin films Electron microscopy Thermal conductivity
Subjects:	Materials Science
Divisions:	UNSPECIFIED
Depositing User:	Dr. Rajpal Walke
Date Deposited:	21 Sep 2016 11:50
Last Modified:	21 Sep 2016 11:50
URI:	http://npl.csircentral.net/id/eprint/1778

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