Effect of Post Growth Annealing on the Structural and Electrical Properties of ZnO/CuO Composite Nanostructures

In the present work, ZnO/CuO composite nanostructures have been grown on fluorine doped tin oxide coated glass substrate by aqueous chemical growth method. To observe the effect of post growth annealing (500 degrees C, 1 min) on the structural properties of ZnO nanorods scanning electron microscope and X-ray diffraction techniques have been utilized. SEM images of post growth annealed (post growth annealed) sample reveal that the average diameter of ZnO NRs has considerably increased in comparison with as grown sample. Moreover after post growth annealing the ZnO NRs showed more clearly hexagonal wurtzite structure. Beside this the NRs are also uniform and well aligned with a high aspect ratio of similar to 10. In XRD pattern the strongly intense (002) peak of the post growth annealing sample suggest that the crystal quality of the NRs have also been improved significantly. Since the structural improvement have a significant impact on charge transport properties as well, therefore the effect of post growth annealed has also been investigated by the electrical characterization of ZnO/CuO based heterojunction. The current-voltage measurements of the post growth annealed sample showed improvement in the current in comparison with as grown sample. The impedance study has also confirmed that the post growth annealed has influence on the electrical properties. The presented post growth annealed heterojunction of ZnO/CuO may have space in applications like sensors and oxide based diodes in the devices fabrication.