Study of physical properties of carbon nanotube thin films deposited by DC magnetron sputtering

Cu-incorporated amorphous carbon thin films containing carbon nanotubes have been prepared by DC-magnetron sputtering using a bi-component Cu-C composite target. The properties of the films have been investigated using X-ray diffraction, energy dispersive X-ray analysis, atomic force microscopy, Furrier transform infrared, Raman and UV-Vis spectroscopies. The results show that the films on a large scale are amorphous with major distorted sp2 graphite bonds, but carbon nanotubes are locally formed in the bulk of the films. Sputtering simulations show that the chemical composition of the films is Cu0.066C0.934. Cu addition results in the formation of a new type of carbon nanotube (CNT) with new radial breathing modes located at 236 cm−1. Cu induces an increase in the density of defects due to bundles of CNTs. This has also been identified in the optical spectroscopy with the observation of a reduction in the band gap with more than 1 eV. Moreover, films are transparent in the visible range and highly reflective in the mid-infrared region, and their sheet resistance is comparable to that of conventional transparent conductive electrodes.