Effect of Annealing Temperature on Morphology and Electrical Property of Hydrothermally-Grown ZnO Nanorods/p-Si Heterojunction Diodes

In this study, ZnO nanorods (NRs) were synthesized using the hydrothermal method, and the effects of annealing temperature (150 degrees C-600 degrees C) on morphology, crystallinity, defects states of the NRs, and electrical property of the n-type ZnO NRs/p-type Si heterojunction diodes were investigated. No appreciable changes in the morphology and crystal structure of the ZnO NRs were observed with increasing annealing temperature up to 450 degrees C. As the temperature increased to 600 degrees C, the average length and diameter of the NRs decreased due to the partial melting and sintering in the NRs. From the X-ray photoelectron spectroscopy (XPS) results, the concentration of internal oxygen vacancies decreased with increasing annealing temperature to 450 degrees C due to thermal diffusion of oxygen vacancies to the surface. The electrical conductivity of the NRs increased to 450 degrees C, which was attributed to the increased crystallinity and low defects concentration (oxygen vacancy) in the NRs. Conversely, the electrical conductivity degraded at 600 degrees C due to the decreased effective contact area.