Transmission-path dependent electron hopping transport in thin films and nanorods of NiO

The present study demonstrates how the length and dimensionality of electron transmission-paths and temperature impact the electron hopping transport in NiO thin films and nanorods. The NiO nanorods and thin films of varying thicknesses were synthesized using physical vapor deposition techniques. The thin films of various thicknesses offer two-dimensional (2D) transmission-paths of varying lengths, whereas nanorods provide confined one-dimensional (1D) transmission-paths for the conduction of electrons. Also, the current-voltage characteristics of 2D and 1D transmission-paths in thin films and nanorods are measured at varying temperatures. The thin films and nanorods of NiO display a characteristic transition in conduction of electrons at a temperature of ∼180 K, which distinguishes the two kinds of electron conduction mechanisms, viz., the nearest-neighbor hopping (NNH) and variable range hopping (VRH). The analysis of the NNH and VRH mechanism quantifies the activation energy, localization lengths, probable hopping distance, and hopping energy of electrons through 2D and 1D transmission-paths at various temperatures. The quantification of these various figure-of-merits proves that the electron hopping transport in nanorods and thin films is quintessentially influenced due to the lengths and dimensionality of transmission-paths and temperature.