Temperature-Dependent Resistivity of Nanowires

The lower carrier density of the 80-nm nanowires compared to bulk bismuth is due to the smaller band overlap in the former. For the 40-nm bismuth nanowires, the carrier density has a temperature dependence similar to bulk bismuth at high temperatures, but it drops rapidly with decreasing temperature at low temperatures. Because the carrier density is highly dependent on wire diameter, the transport properties of bismuth nanowires are expected to be highly sensitive to wire diameter, as will be shown experimentally in the section temperature-dependent resistivity of nanowires. ... 

Transport properties (continued.) semiclassical model, 192-193 temperature-dependent resistivity of nanowires, 193-198 Triplet sites on supports, 63-64 Tungsten species, SiC>2-supported, 63 Turnover numbers (TON), nanostructured materials, 6... 

Figure 19(a) shows the temperature dependence of resistance R(T) for bismuth nanowire arrays (dw = 7 - 200 nm) synthesized by vapor deposition and measured by Heremans et al. (2000). Hong et al. (1999) reported similar resistance measurements on bismuth wires of larger diameters (200 nm to 2, uni) prepared by electrochemical deposition (Fig. 19(b)). These two studies... 

Fig. 19. (a) Measured temperature dependence of resistance for bismuth nanowire arrays of various wire diameters dw (Heremans et al, 2000). (b) R(T)/R(290 K) for bismuth wires of larger dw measured by Hong et al. (1999). (c) Calculated R(T)/R(300 K) of 36-nm and 70-nm bismuth nanowires (Lin et al, 2000b). The dashed curve refers to a 70-nm poly crystalline wire with increased boundary scattering. 

In conclusion, the phonon-assisted tunnelling model describes well both the temperature-dependent I-V data and dependence of resistance on temperature in a wide range of temperatures. The electric field strength at which tunnelling occurs was estimated to be in the range of 1-5 MV/m. The densities of localized states in the interface layer were found to be about lO cm in the Bi-rich and 3x10 cm in the Sb-rich BiSbTe nanowires. 

PEDOT PSS nanowire (Figure 10.41) [101,102]. The temperature dependence of the resistance indeed followed Mott VRH for a 1-D system, i.e., p T) oc exp (TMott/T). Tiviott was determined to be 1900 K, which is similar to that of PEDOT PSS thin films. 

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