Defect-concentration dependence of electrical transport mechanisms in CuO nanowires.

Investigations of the transport mechanisms of individual nanowires are important for advancing their use in applications. Based on statistical results for the temperature-dependent electrical characteristics of individual CuO nanowires, and by characterizing them using transmission electron microscopy, we have found that the defect concentration is the most important parameter affecting electron transport in nanowires. Space-charge-limited currents can be observed for sufficiently high applied voltages, for example about 10 V. In the ohmic regime, before the current-voltage curves of nanowires enter the trap-filling stage, three main transport mechanisms have been proposed. They are related to the defect concentrations and include combinations of defect-induced nearest-neighbor hopping, trap activation, and intrinsic excitation. Numerical calculations using the model to fit the experimental data agree very well, confirming the proposed transport mechanisms.