The present work investigates charge transport characteristics of single TiO2 nanotubes and CuO nanowires. In the first part, we have fabricated TiO2 nanotubes with single and double-walled morphologies to study their effect on charge transport in individual nanotubes. Electric field and temperature-dependent J-V characteristics reveal higher conductivity and lower activation energy in single-walled nanotubes than that in double-walled nanotubes. We have calculated energies associated with shallow and intermediate defect states that contribute to two thermal activation processes. Further, we have also studied electrical breakdown in a single nanotube occurring due to crack formation and localized heating-driven electromigration. In addition, charge transport in nanotubes prepared under different annealing conditions reveals that mixed-phase (anatase/rutile) nanotube with a higher rutile content leads to a decrease in the conductivity and space charge limited conduction (SCLC) occurs in these nanotubes. These studies establish a greater insight into the electrical conduction and breakdown behavior of single TiO2 nanotubes and help in designing nanotube-based nanoelectronic devices.
In the second part of the thesis, we have studied charge transport in single CuO nanowires grown by thermal oxidation of Cu foil. We found an anomalous behavior in J-V characteristics, wherein a decrease in current density with an increase in nanowire diameter has been observed. This is attributed to the presence of the secondary Cu2O phase in the thicker nanowires, which acts as a hole sink and hinders charge transport in these p-type materials. We have also calculated trap density for thinner and thicker nanowires. Finally, photodetectors based on single bare CuO and CuO/Cu2O core-shell nanowires are fabricated, which show better photodetection by core-shell architecture due to heterostructure formation and Ohmic junction at the Cu2O-Pd (electrode) interface.