Different effects of grain boundary scattering on charge and heat transport in polycrystalline platinum and gold nanofilms

Abstract

The in-plane electrical and thermal conductivities of several polycrystalline platinum and gold nanofilms with different thicknesses are measured in a temperature range between the boiling point of liquid nitrogen (77 K) and room temperature by using the direct current heating method. The result shows that both the electrical and thermal conductivities of the nanofilms reduce greatly compared with their corresponding bulk values. However, the electrical conductivity drop is considerably greater than the thermal conductivity drop, which indicates that the influence of the internal grain boundary on heat transport is different from that of charge transport, hence leading to the violation of the Wiedemann–Franz law. We build an electron relaxation model based on Matthiessen's rule to analyse the thermal conductivity and employ the Mayadas & Shatzkes theory to analyse the electrical conductivity. Moreover, a modified Wiedemann–Franz law is provided in this paper, the obtained results from which are in good agreement with the experimental data.

Correlation of Material Structure and Electronic Properties in 2D Platinum-Diselenide-based Devices

“…A second factor is the barrier height presented by the grain boundaries. In our PtSe2 films, the effects can be captured in a resistivity model for polycrystalline films, [41,42] which qualitatively captures the experimental observations of an increase in resistivity for a film with both decreasing crystallite size and increasing grain boundary density. The model is described in detail in the SI (Figure S13).…”

“…Finally, we measure and analyze the electronic properties and the piezoresistive gauge factor (GF) on devices with transferred PtSe2 films. We then discuss the structural composition and variations in the nanocrystalline films and present a model correlating the polycrystalline electrical resistivity and its change with temperature [41,42] .…”

Dominant Energy Carrier Transitions and Thermal Anisotropy in Epitaxial Iridium Thin Films

“…Large Lorenz numbers are also observed with thin films of Pt [ 22 ] and Au, [ 21 ] attributed to quantum mechanical reflection of electrons at film/substrate boundaries that impedes the transport of charge over that of heat. [ 50 ]…”

Influence of Impurities on the Front Velocity of Sputter Deposited Al/CuO Thermite Multilayers

“…This statement probably also holds for the films deposited in the most impure conditions ( ) as the maximum measured resistivity of the multilayer was 1.850 × 10 −8 m. The obtained resistivity values were converted into thermal conductivities via the application of the Wiedemann–Franz law. This is an approximation because it is known that the Wiedemann–Franz or the Lorenz ratio can be a function of the domain size [ 27 ]. The ratio between grain size and the electron mean free path drives this latter dependency.…”

“…The obtained resistivity values were converted into thermal conductivities via the application of the Wiedemann-Franz law. This is an approximation because it is known that the Wiedemann-Franz or the Lorenz ratio can be a function of the domain size [27]. The ratio between grain size and the electron mean free path drives this latter dependency.…”