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A physics-based flexural phonon-dependent thermal conductivity model for single layer graphene

Verma, Rekha and Bhattacharya, Sitangshu and Mahapatra, Santanu (2013) A physics-based flexural phonon-dependent thermal conductivity model for single layer graphene. In: SEMICONDUCTOR SCIENCE AND TECHNOLOGY, 28 (1).

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Official URL: http://dx.doi.org/10.1088/0268-1242/28/1/015009

Abstract

In this paper, we address a physics-based closed-form analytical model of flexural phonon-dependent diffusive thermal conductivity (kappa) of suspended rectangular single layer graphene sheet. A quadratic dependence of the out-of-plane phonon frequency, generally called flexural phonons, on the phonon wave vector has been taken into account to analyze the behavior of kappa at lower temperatures. Such a dependence has further been used for the determination of second-order three-phonon Umklapp and isotopic scatterings. We find that these behaviors in our model are best explained through the upper limit of Debye cut-off frequency in the second-order three-phonon Umklapp scattering of the long phonon waves that actually remove the thermal conductivity singularity by contributing a constant scattering rate at low frequencies and note that the out-of-plane Gruneisen parameter for these modes need not be too high. Using this, we clearly demonstrate that. follows a T-1.5 and T-2 law at lower and higher temperatures in the absence of isotopes, respectively. However in their presence, the behavior of kappa sharply deviates from the T-2 law at higher temperatures. The present geometry-dependent model of kappa is found to possess an excellent match with various experimental data over a wide range of temperatures which can be put forward for efficient electro-thermal analyses of encased/supported graphene.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to IOP PUBLISHING LTD, ENGLAND
Department/Centre: Division of Electrical Sciences > Electronic Systems Engineering (Formerly Centre for Electronic Design & Technology)
Depositing User: Francis Jayakanth
Date Deposited: 18 Feb 2013 09:01
Last Modified: 18 Feb 2013 09:01
URI: http://eprints.iisc.ac.in/id/eprint/45779

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