Effect of channel length on single walled carbon nanotubes thin film characteristics deposited via spray coating technique

Abstract

Single-Walled Carbon Nanotubes (SWCNTs) have exceptional electronic properties and can be formed as thin film via spray coating for various device applications. This paper presents the optical and electrical characterization of spray coated SWCNT thin films of varying channel length dimensions to demonstrate the reproducibility and controllability of the spray coating method used. SWCNT thin films were spray coated using air-brush nozzle on separate substrates before patterning top contacted metal electrodes of channel lengths 0.5, 1.0, 2.0, and 3.0 mm, respectively. Optical characterizations via FESEM and AFM were carried out to evaluate the film morphology. Subsequently, electrical characterization based on 2-terminal IV measurements were carried out. From the optical characterization, the SWCNT thin films exhibit high uniformity. From the electrical characterization, it was shown that the spray coated SWCNT thin films exhibit high conductivity and consistent current that are inversely proportional to the channel length. At 1 V electrode bias, the corresponding currents are 91.80 μA (0.5 mm), 34.80 μA (1 mm), 14 μA (2 mm) and 1.96 μA (3 mm). The average resistivity recorded for each channel lengths are 0.41 μΩ.m (0.5 mm), 198 μΩ.m (1 mm), 418 μΩ.m (2 mm) and 2150 μΩ.m (3 mm). These consistent observations indicate that spray coated SWCNTs thin films exhibit high performance and reproducibility for various electronical applications.