Electrical and Thermal Transport through Silver Nanowires and Their Contacts: Effects of Elastic Stiffening

Abstract

Silver nanowires have been widely adopted as nanofillers in composite materials used for various applications. Electrical and thermal properties of these composites are critical for proper device operation, and highly depend on transport through the nanowires and their contacts, yet studies on silver nanowires have been limited to one or two samples and no solid data have been reported for individual contacts. Through systematic measurements of silver nanowires of different sizes, we show that the Lorenz number increases with decreasing wire diameter and has a higher value at wire contacts. Examination of the corresponding electrical and thermal conductivities indicates that these changes are due to contributions of phonons that become more important as a result of elastic stiffening. The derived contact thermal conductance per unit area between silver nanowires is ∼10 times that between carbon nanotubes. This helps to explain the more significant thermal conductivity enhancement of silver nanowires-based composites.

First-principles based analysis of thermal transport in metallic nanostructures: Size effect and Wiedemann-Franz law

“…A recent careful experimental measurement reveals that when excluding the contact resistance, the Lorentz ratio of silver nanowires is close to the Sommerfeld value [11], which is consistent with our findings (silver also has a small phonon contribution, which is similar to Au). It indicates that there may be some uncertainties in earlier experimental measurements due to the challenge in dealing with contact resistance.…”

“…Due to the miniaturization of electronic devices, metallic nanostructures (nanofilms and nanowires) play an imperative role in electronic applications ranging from interconnects to sensors [1][2][3]. Since effective heat dissipation is crucial to ensure the reliability of electronic devices [4], the thermal conductivity of metallic nanostructures is crucial [5][6][7][8][9][10][11]. Over the past two decades, there have been many discussions on thermal transport in metallic nanostructures [9,10,[12][13][14][15][16][17][18].…”

Plasmon-enhanced photoresponse of single silver nanowires and their network devices

“…The significantly improved resistance value shows that the contact resistance of the device is reduced by fusing the contact metal to the Ag NW. 33 It can be speculated that the contact resistance improvement is due to the SPP-assisted heating generated at the contact region or due to Joule heating as the device is under bias during SPCM measurements. 34 Another possibility that may lead to the decrease in the resistance is the interface reconstruction due to electromigration in Ag NWs.…”

Contact Thermal Resistance between Silver Nanowires with Poly(vinylpyrrolidone) Interlayers

“…10 On the other hand, recent experimental results indicate that the contact thermal resistance between individual silver nanowires (AgNWs) could be ∼20 times lower than that between similar diameter MWCNTs. 11 In terms of thermal conductance per unit area, the value for contacts between AgNWs could be one order of magnitude higher than that between MWCNTs, which is partially due to lack of electron reflection back into the emitting wires. 10,11 This is consistent with the higher thermal conductivity values typically displayed by polymer composites utilizing metallic nanofillers.…”

“…11 In terms of thermal conductance per unit area, the value for contacts between AgNWs could be one order of magnitude higher than that between MWCNTs, which is partially due to lack of electron reflection back into the emitting wires. 10,11 This is consistent with the higher thermal conductivity values typically displayed by polymer composites utilizing metallic nanofillers. 12,13 However, one outstanding issue is that, in nanocomposites, the contact morphology between nanofillers could be much more complex, and instead of direct contacts between nanofillers, there is often a thin polymer layer between neighboring nanofillers.…”