A comprehensive study of thermoelectric and transport properties of β-silicon carbide nanowires

Abstract

The temperature dependence of the Seebeck coefficient, the electrical and thermal conductivities of individual β-silicon carbide nanowires produced by combustion in a calorimetric bomb were studied using a suspended micro-resistance thermometry device that allows four-point probe measurements to be conducted on each nanowire. Additionally, crystal structure and growth direction for each measured nanowire was directly obtained by transmission electron microscopy analysis. The Fermi level, the carrier concentration, and mobility of each nanostructure were determined using a combination of Seebeck coefficient and electrical conductivity measurements, energy band structure and transport theory calculations. The temperature dependence of the thermal and electrical conductivities of the nanowires was explained in terms of contributions from boundary, impurity, and defect scattering.

Thermoelectric properties of SnSe nanowires with different diameters

“… 20 for smaller diameters (130 nm, 190 nm and 390 nm) the thermal conductivity remains practically constant or with a small increase with temperature in the 130 nm wire. This behavior is consistent with the increasing contribution of phonons surface scattering in thin nanowires 37 , 41 , 42 although we note that a recent thermal conductivity accumulation study by Guo et al . 32 found negligible contribution to the lattice thermal conductivity of phonons with wavelengths above ~100 nm.…”

“…3b ) is dominated by phonon transport (Fig. 5d ) as previously observed in nanowires of other semiconductor materials 22 , 37 . For comparison, Fig.…”

“…After synthesis, the nanowires were detached from the substrates by sonication in ethanol and dispersed on a Si substrate for inspection and micromanipulation. Nanowires with different diameters were selected and transported to suspended microdevices to measure S , σ , and κ , according to the procedure detailed in previous studies 34 – 37 , (see Supplementary Information, Figure S2 for experimental measurement method details). Figure 2 shows a close-up SEM image of a typical SnSe nanowire integrated onto the measuring microdevices.…”

“…The transport properties were calculated based on the Boltzmann transport equation under the rigid band and constant relaxation time approximations as implemented on the BoltzTraP package 48 . This numerical package has been previously used to study SnSe materials with good results 24 , 26 , 29 , 31 , 37 , 49 . BoltzTraP package calculated the Seebeck coefficient S, the electrical conductivity σ and thermal conductivity κ e according to the following expressions: where, ; is the transport distribution function, μ is chemical potential, e is the electronic charge, τ is the relaxation time, f 0 is the fermi function, v k is the group velocity and δ ( E − E ( k )) is the delta function.…”

Preparation of Highly Flexible SiC Nanowires by Fluidized Bed Chemical Vapor Deposition

“…Since the discovery of carbon nanotubes in 1991, carbon based one‐dimensional (1D) nanostructures such as wires, rods, belts, and tubes have attracted continuous research attentions because of their many shape and size dependent properties and potential applications for construction nanodevices . Among these nanostructures, silicon carbide (SiC) nanowires have been extensively studied because of their unique physical and chemical properties such as electrical transport, thermoelectricity, photocatalysis, field emission, hydrophobicity and super‐plasticity properties. Due to the large band gap, good carrier mobility, and property of chemical inertness, nanodevices made with SiC nanowires have high resistance to corrosion and can be operated at high temperatures, high powers, high frequencies, and in harsh environments.…”