Effect of Al incorporation on morphology and electrical conductivity of ZnO nanorods prepared using hydrothermal method

Al-doped ZnO (AZO) nanorods (NRs) with different doping contents (actual content of 1.7%-4.9%) were synthesized on p-type Si substrates using the hydrothermal method, and n-AZO NRs/p-Si heterojunction diodes were then fabricated using the NRs. The electrical property, chemical bonding states, and morphology of the AZO NRs were investigated through various analysis tools. The AZO NRs grew along the c-axis [001] direction with a hexagonal wurtzite structure, and the crystal structure and orientation of the NRs were not significantly influenced by the Al incorporation. On the other hand, while the average length and diameter of the AZO NRs decreased with increasing Al content, the density increased. From the XPS result, we found that the oxygen vacancy of the AZO increased as the Al content was increased due to the large surface to volume ratio. The current-voltage (I-V ) curves revealed that electrical conductivity increased with increasing Al doping because of the increased number of charge carriers (electrons) provided by the Al³⁺ ions and oxygen vacancies.