Semiconducting Carbon Nanotubes Embedded in a Metallic Film for a Thermistor Device with an Adjustable Temperature Coefficient and Reduced Noise Source Activities

Abstract

On the other hand, a key issue in using sSWCNT channels for device applications (i.e., a transistor, temperature sensors) can be the interface between sSWCNTs and metal electrodes. [10] Previous reports show that the formation of Schottky barriers between sSWCNT and metal electrodes may increase the contact resistance and often electrical noises, resulting in the degradation of overall device performances. [11,12] However, the effect of sSWCNTs on the nanoscale transport properties (i.e., conductivity, charge trap activities) of the metal-sSWCNT interface structures has not been clearly understood yet. Herein, we report semiconducting SWCNTs embedded in Au films for a thermistor device with an adjustable temperature coefficient and reduced noise source activities. In this work, an Au thin film was deposited on sSWCNT network layers to build a thermistor device. Then, a scanning noise microscopy (SNM) method was utilized to map the resistivity and noise source activities on the hybrid film with a nanoscale resolution. The sSWCNT/ Au hybrid thin films showed a linear temperature-resistance dependence with minimal hysteresis. Interestingly, sSWCNTmetal hybrid films with rather thin Au films exhibited a negative temperature coefficient of resistance (TCR) values, while those with rather thick Au films showed a positive TCR. It indicates we can control the TCR values simply by changing the Au film thickness. The resistivity map measured by the SNM method exhibited three times smaller resistivity on the Au films with sSWCNTs, showing that sSWCNTs can work as a high conductance current path and enhance the conductivity of the film. Furthermore, we observed the 18 times smaller noise source activities in the region with sSWCNTs. These results show that sSWCNTs in thin metallic films can enhance the conductivity and reduce electrical noises, enabling high-performance device applications such as thermistors.