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Study of conductance fluctuations (1/f alpha noise) in metallic nanowires

Bid, Aveek and Raychaudhuri, Arup K (2004) Study of conductance fluctuations (1/f alpha noise) in metallic nanowires. In: SPIE: Fluctuations and Noise in Materials, 26 May, Maspalomas Gran Canaria Island,Spain, Vol.5469, 320-327.

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We have studied the conductance fluctuations in silver nanowires in the temperature range 4K to 375K. The nanowires with an average diameter of 15nm were electrochemically deposited using polycarbonate membrane as template. Principal motivation is to study low frequency defect relaxations in the nanowires that give rise to conductance fluctuations with a spectral power $S(f) \sim 1/f^{alpha}$ . The Ag nanowires, stabilized at 400K with a current of few mA, show metallic temperature dependence. The S(f) was measured with a psuedo 4 probe ac technique with rms current of few tens of µA. We find that $S_V(f)$ (which is $\sim 1/f^{alpha}$) shows a rapid rise at around 220K as T is increased along with an enhancement in the exponent alpha. The exponent alpaha $\approx 1-1.1$ for T<220 and it increases to alpha $\approx 1.4$ at T=375K. In the same temperature range S(f) rises by an order of magnitude. We analyze the data using a model assuming that there are two components to the $1/f^{alpha}$ fluctuations--one arising from relaxation of local defects give alpha $\approx 1.$ The other arises from the long-range diffusion of defects characterized by alpha $\approx 3/2.$ It is seen that for T < 220K the noise arises mainly from local defect relaxation and the temperature dependence of a follows the Dutta-Horn model. Above this temperature the contribution from long-range diffusion dominates with the noise becoming thermally activated with an activation energy (~300meV). Interestingly the activation energy is similar to but somewhat higher than that seen in micron sized films.

Item Type: Conference Paper
Publication: SPIE-The International Society for Optical Engineering
Publisher: The International Society for Optical Engineering
Additional Information: The copyright belongs The International Society for Optical Engineering.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 11 Dec 2006
Last Modified: 27 Aug 2008 11:57
URI: http://eprints.iisc.ac.in/id/eprint/6629

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