Nanometrology: Absolute Seebeck coefficient of individual silver nanowires

Abstract

Thermoelectric phenomena can be strongly modified in nanomaterials. The determination of the absolute Seebeck coefficient is a major challenge for metrology with respect to micro- and nanostructures due to the fact that the transport properties of the bulk material are no more valid. Here, we demonstrate a method to determine the absolute Seebeck coefficient S of individual metallic nanowires. For highly pure and single crystalline silver nanowires, we show the influence of nanopatterning on S in the temperature range between 16 K and 300 K. At room temperature, a nanowire diameter below 200 nm suppresses S by 50% compared to the bulk material to less than S = 1 μVK−1, which is attributed to the reduced electron mean free path. The temperature dependence of the absolute Seebeck coefficient depends on size effects. Thermodiffusion and phonon drag are reduced with respect to the bulk material and the ratio of electron-phonon to phonon-phonon interaction is significantly increased.

Semimetal to semiconductor transition in Bi/TiO2 core/shell nanowires

“…The spatial limitation leads to more surface scattering, a reduced charge carrier mean free path and as a result to a reduction of the thermodiffusion contribution (from both electrons and holes) to the absolute Seebeck coefficient. 15,16 Furthermore, the slightly increase of S at around T ¼ 100 K may be attributed to the inuence of phonon drag.…”

Scanning Thermal Microscopy and Ballistic Phonon Transport in Lateral Spin Valves

“…We have measured the total thermal voltage and BLR as a function of electrode separation over a range of temperatures. To fit the temperature dependence we used two fitting parameters: the temperature of the injector and the thermal conductance of the Ag/SiO 2 interface, K. Measured detector voltages were converted to temperatures using the published values of the thermopower of Ag [41] and Py [42] nanowires combined into an effective Seebeck coefficient. We extrapolated estimates to low temperatures where data were not available.…”

Semimetal to semiconductor transition in $\text{Bi}/\text{TiO}_{2}$ core/shell nanowires

“…This can be attributed to the small diameter of the Bi core that is only 95 nm without the shell. The spatial limitation leads to more surface scattering, a reduced charge carrier mean free path and as a result to a reduction of the absolute Seebeck coefficient [14,19]. Bi/TiO 2 2 (470 nm) shows an increase of the absolute Seebeck coefficient compared to that of Bi nanowires and Bi bulk.…”

“…However, the combined full thermoelectric characterization of individual Bi-based core/shell nanowires, in which all transport parameters (σ, S and λ) are determined on one and the same nanowire, remains an open issue. Here, we demonstrate the full thermoelectric transport and structural characterization of individual core/shell nanowires [12][13][14] and investigate titanium dioxide (TiO 2 ) as insulating shell material for Bibased nanowires and compare this to Bi and Bi/Te nanowires. We detect the transition from the semiconducting to semimetallic state and vice versa and discuss the influence of the shell material on the thermoelectric properties of individual Bi-based nanowires.…”