Co-sputtered metal and polymer nanocomposite films and their electrical responses for gas sensing application

Abstract Titanium and polytetrafluoroethylene (Ti–PTFE) nanocomposite thin films were successfully fabricated on glass substrates using a combination of dc and rf magnetron sputtering. When the Ti–PTFE composites were prepared at below the percolation threshold i.e. 27% metal volume filling ( F ), Ti clusters with the average sizes of 7 ± 2 nm were found. As the Ti content was increased above the percolation threshold ( F  = 62%), the connecting regions of Ti were formed within the polymer matrix and the electrical property changed rapidly from insulator-like to metal-like properties. The Ti–PTFE composites prepared near the percolation threshold showed the electrical response to different volatile organic compounds (VOCs). The sensitivity significantly depended upon the VOCs concentrations. These composites devices showed the presence of distinct chemical bonds of C C, C CF, C F and CF 2 and TiF in TiO 2 on the surface as investigated by X-ray photoelectron spectroscopy (XPS) while the surface morphology, characterized by atomic force microscopy (AFM) presented the root mean square (RMS) surface roughness of 13.3 nm. Cross-section transmission electron microscopy (TEM) images of the device revealed Ti clusters dispersed in PTFE matrix with particle sizes varied between 10 nm and 30 nm.