Nb concentration dependent nanoscale electrical transport properties of granular Ti_1-xNb_xN thin films

Granular Ti_1-xNb_xN thin films, 0 ≤ x ≤ 0.77, were deposited on borosilicate glass substrates by RF magnetron sputtering. Conductive-atomic force microscopy (C-AFM) was employed to study the local electrical transport properties of Ti_1-xNb_xN thin films. Topography images reveal that the grain size in the films increased from 30 to 90 nm, as x increased from 0 to 0.77. For a constant applied voltage of 1 V, the local leakage current in Ti_1-xNb_xN films increased with an increase in x value. The measured current is in the order of nA and its flow is filamentary in nature. Current-voltage characteristics measured at different locations on each current image revealed that the local resistance drastically decreased with an increase in Nb concentration. Electron-grain boundary scattering and the presence of native oxide states are responsible for the increase in the local electrical resistance of the films.