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

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 similar to 10 times that between carbon nanotubes. This helps to explain the more significant thermal conductivity enhancement of silver nanowires-based composites.