Carrier mobility and transport mechanism in single-walled carbon nanotube (SWCNT) random network studied using impedance spectroscopy

Abstract

Single-walled carbon nanotube (SWCNT), in its random network form, is a very attractive candidate for flexible electronic applications due to its excellent electrical and mechanical properties. In this work, we have demonstrated a flexible inkjet-printed SWCNT metal–semiconductor–metal structure and evaluate its electrical properties using current–voltage (I–V), capacitance–voltage (C–V) characteristics, and impedance spectroscopy Z(f) as a function of temperature. Furthermore, the sample was modeled as an RC circuit, and mobility was investigated by three different methods—Nyquist/Cole–Cole plot [−Im(Z) vs Re(Z)], −Im(Z) vs Frequency, and phase (Theta) vs Frequency. Then, the conduction mechanism was further investigated, and popular models of transport such as variable range hopping and fluctuation induced tunneling are not applicable. The ln(mobility) is found to be proportional to E−1/4 and T2, over a wide range of field E and temperature T. The temperature dependence of mobility is consistent with the prediction of percolation-tunneling model of transport recently proposed for such CNT networks.